"ctypes" --- A foreign function library for Python
**************************************************

**Source code:** Lib/ctypes

======================================================================

"ctypes" is a foreign function library for Python.  It provides C
compatible data types, and allows calling functions in DLLs or shared
libraries.  It can be used to wrap these libraries in pure Python.

This is an *optional module*. If it is missing from your copy of
CPython, look for documentation from your distributor (that is,
whoever provided Python to you). If you are the distributor, see
Requirements for optional modules.


Didacticiel de *ctypes*
=======================

Remarque : le type "c_int" du module apparaît dans certains de ces
exemples. Sur les plates-formes où "sizeof(long) == sizeof(int)", ce
type est un alias de "c_long". Ne soyez donc pas surpris si "c_long"
s'affiche là où vous vous attendiez à "c_int" — il s'agit bien du même
type.


Chargement des DLL
------------------

"ctypes" exports the "cdll", and on Windows "windll" and "oledll"
objects, for loading dynamic link libraries.

You load libraries by accessing them as attributes of these objects.
"cdll" loads libraries which export functions using the standard
"cdecl" calling convention, while "windll" libraries call functions
using the "stdcall" calling convention. "oledll" also uses the
"stdcall" calling convention, and assumes the functions return a
Windows "HRESULT" error code. The error code is used to automatically
raise an "OSError" exception when the function call fails.

Modifié dans la version 3.3: En Windows, les erreurs levaient
auparavant une "WindowsError", qui est maintenant un alias de
"OSError".

Here are some examples for Windows. Note that "msvcrt" is the MS
standard C library containing most standard C functions, and uses the
"cdecl" calling convention:

   >>> from ctypes import *
   >>> print(windll.kernel32)
   <WinDLL 'kernel32', handle ... at ...>
   >>> print(cdll.msvcrt)
   <CDLL 'msvcrt', handle ... at ...>
   >>> libc = cdll.msvcrt
   >>>

Windows ajoute le suffixe habituel ".dll" automatiquement.

Note:

  Accéder à la bibliothèque standard C par "cdll.msvcrt" utilise une
  version obsolète de la bibliothèque qui peut avoir des problèmes de
  compatibilité avec celle que Python utilise. Si possible, mieux vaut
  utiliser la fonctionnalité native de Python, ou bien importer et
  utiliser le module "msvcrt".

Other systems require the filename *including* the extension to load a
library, so attribute access can not be used to load libraries. Either
the "LoadLibrary()" method of the dll loaders should be used, or you
should load the library by creating an instance of "CDLL" by calling
the constructor.

For example, on Linux:

   >>> cdll.LoadLibrary("libc.so.6")
   <CDLL 'libc.so.6', handle ... at ...>
   >>> libc = CDLL("libc.so.6")
   >>> libc
   <CDLL 'libc.so.6', handle ... at ...>
   >>>

On macOS:

   >>> cdll.LoadLibrary("libc.dylib")
   <CDLL 'libc.dylib', handle ... at ...>
   >>> libc = CDLL("libc.dylib")
   >>> libc
   <CDLL 'libc.dylib', handle ... at ...>


Accès aux fonctions des DLL chargées
------------------------------------

Les fonctions sont alors des attributs des objets DLL :

   >>> libc.printf
   <_FuncPtr object at 0x...>
   >>> print(windll.kernel32.GetModuleHandleA)
   <_FuncPtr object at 0x...>
   >>> print(windll.kernel32.MyOwnFunction)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "ctypes.py", line 239, in __getattr__
       func = _StdcallFuncPtr(name, self)
   AttributeError: function 'MyOwnFunction' not found
   >>>

Note that win32 system dlls like "kernel32" and "user32" often export
ANSI as well as UNICODE versions of a function. The UNICODE version is
exported with a "W" appended to the name, while the ANSI version is
exported with an "A" appended to the name. The win32 "GetModuleHandle"
function, which returns a *module handle* for a given module name, has
the following C prototype, and a macro is used to expose one of them
as "GetModuleHandle" depending on whether UNICODE is defined or not:

   /* ANSI version */
   HMODULE GetModuleHandleA(LPCSTR lpModuleName);
   /* UNICODE version */
   HMODULE GetModuleHandleW(LPCWSTR lpModuleName);

*windll* n'en choisit pas une par magie, il faut accéder à la bonne en
écrivant explicitement "GetModuleHandleA" ou "GetModuleHandleW" et en
les appelant ensuite avec des objets octets ou avec des chaînes de
caractères, respectivement.

Les DLL exportent parfois des fonctions dont les noms ne sont pas des
identifiants Python valides, comme ""??2@YAPAXI@Z"". Dans ce cas, il
faut utiliser "getattr()" pour accéder à la fonction :

   >>> getattr(cdll.msvcrt, "??2@YAPAXI@Z")
   <_FuncPtr object at 0x...>
   >>>

Sous Windows, certaines DLL exportent des fonctions à travers un
indice plutôt qu'à travers un nom. On accède à une fonction en
indiçant l'objet DLL avec son index :

   >>> cdll.kernel32[1]
   <_FuncPtr object at 0x...>
   >>> cdll.kernel32[0]
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "ctypes.py", line 310, in __getitem__
       func = _StdcallFuncPtr(name, self)
   AttributeError: function ordinal 0 not found
   >>>


Appel de fonctions
------------------

You can call these functions like any other Python callable. This
example uses the "rand()" function, which takes no arguments and
returns a pseudo-random integer:

   >>> print(libc.rand())
   1804289383

On Windows, you can call the "GetModuleHandleA()" function, which
returns a win32 module handle (passing "None" as single argument to
call it with a "NULL" pointer):

   >>> print(hex(windll.kernel32.GetModuleHandleA(None)))
   0x1d000000
   >>>

Une "ValueError" est levée quand on appelle une fonction "stdcall"
avec la convention d'appel "cdecl" et vice-versa :

   >>> cdll.kernel32.GetModuleHandleA(None)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   ValueError: Procedure probably called with not enough arguments (4 bytes missing)
   >>>

   >>> windll.msvcrt.printf(b"spam")
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   ValueError: Procedure probably called with too many arguments (4 bytes in excess)
   >>>

Pour déterminer la convention d'appel, il faut consulter l'en-tête C
ou la documentation de la fonction à appeler.

On Windows, "ctypes" uses win32 structured exception handling to
prevent crashes from general protection faults when functions are
called with invalid argument values:

   >>> windll.kernel32.GetModuleHandleA(32)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   OSError: exception: access violation reading 0x00000020
   >>>

There are, however, enough ways to crash Python with "ctypes", so you
should be careful anyway.  The "faulthandler" module can be helpful in
debugging crashes (e.g. from segmentation faults produced by erroneous
C library calls).

"None", integers, bytes objects and (unicode) strings are the only
native Python objects that can directly be used as parameters in these
function calls. "None" is passed as a C "NULL" pointer, bytes objects
and strings are passed as pointer to the memory block that contains
their data (char* or wchar_t*).  Python integers are passed as the
platform's default C int type, their value is masked to fit into the C
type.

Before we move on calling functions with other parameter types, we
have to learn more about "ctypes" data types.


Types de données de base
------------------------

"ctypes" defines a number of primitive C compatible data types:

+---------------------------+---------------------------+---------------------------+---------------------------+
| Types de *ctypes*         | Type C                    | Type Python               | "_type_"                  |
|===========================|===========================|===========================|===========================|
| "c_bool"                  | _Bool                     | "bool"                    | "'?'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_char"                  | char                      | 1-character "bytes"       | "'c'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_wchar"                 | "wchar_t"                 | 1-character "str"         | "'u'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_byte"                  | char                      | "int"                     | "'b'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_ubyte"                 | unsigned char             | "int"                     | "'B'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_short"                 | short                     | "int"                     | "'h'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_ushort"                | unsigned short            | "int"                     | "'H'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_int"                   | int                       | "int"                     | "'i'" *                   |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_int8"                  | "int8_t"                  | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_int16"                 | "int16_t"                 | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_int32"                 | "int32_t"                 | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_int64"                 | "int64_t"                 | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_uint"                  | unsigned int              | "int"                     | "'I'" *                   |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_uint8"                 | "uint8_t"                 | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_uint16"                | "uint16_t"                | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_uint32"                | "uint32_t"                | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_uint64"                | "uint64_t"                | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_long"                  | long                      | "int"                     | "'l'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_ulong"                 | unsigned long             | "int"                     | "'L'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_longlong"              | long long                 | "int"                     | "'q'" *                   |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_ulonglong"             | unsigned long long        | "int"                     | "'Q'" *                   |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_size_t"                | "size_t"                  | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_ssize_t"               | "Py_ssize_t"              | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_time_t"                | "time_t"                  | "int"                     | *                         |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_float"                 | float                     | "float"                   | "'f'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_double"                | double                    | "float"                   | "'d'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_longdouble"            | long double               | "float"                   | "'g'" *                   |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_char_p"                | char* (NUL terminated)    | "bytes" or "None"         | "'z'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_wchar_p"               | wchar_t* (NUL terminated) | "str" or "None"           | "'Z'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_void_p"                | void*                     | "int" or "None"           | "'P'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "py_object"               | PyObject*                 | "object"                  | "'O'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+
| VARIANT_BOOL              | short int                 | "bool"                    | "'v'"                     |
+---------------------------+---------------------------+---------------------------+---------------------------+

Additionally, if IEC 60559 compatible complex arithmetic (Annex G) is
supported in both C and "libffi", the following complex types are
available:

+---------------------------+---------------------------+---------------------------+---------------------------+
| Types de *ctypes*         | Type C                    | Type Python               | "_type_"                  |
|===========================|===========================|===========================|===========================|
| "c_float_complex"         | float complex             | "complex"                 | "'Zf'"                    |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_double_complex"        | double complex            | "complex"                 | "'Zd'"                    |
+---------------------------+---------------------------+---------------------------+---------------------------+
| "c_longdouble_complex"    | long double complex       | "complex"                 | "'Zg'"                    |
+---------------------------+---------------------------+---------------------------+---------------------------+

Modifié dans la version 3.15: The "_type_" types "F", "D" and "G" have
been replaced with "Zf", "Zd" and "Zg".

Il est possible de créer chacun de ces types en les appelant avec une
valeur d'initialisation du bon type et avec une valeur cohérente :

   >>> c_int()
   c_long(0)
   >>> c_wchar_p("Hello, World")
   c_wchar_p(140018365411392)
   >>> c_ushort(-3)
   c_ushort(65533)
   >>>

The constructors for numeric types will convert input using
"__bool__()", "__index__()" (for "int"), "__float__()" or
"__complex__()". This means "c_bool" accepts any object with a truth
value:

   >>> empty_list = []
   >>> c_bool(empty_list)
   c_bool(False)

Ces types étant des mutables, leur valeur peut aussi être modifiée
après coup :

   >>> i = c_int(42)
   >>> print(i)
   c_long(42)
   >>> print(i.value)
   42
   >>> i.value = -99
   >>> print(i.value)
   -99
   >>>

Assigning a new value to instances of the pointer types "c_char_p",
"c_wchar_p", and "c_void_p" changes the *memory location* they point
to, *not the contents* of the memory block (of course not, because
Python string objects are immutable):

   >>> s = "Hello, World"
   >>> c_s = c_wchar_p(s)
   >>> print(c_s)
   c_wchar_p(139966785747344)
   >>> print(c_s.value)
   Hello World
   >>> c_s.value = "Hi, there"
   >>> print(c_s)              # the memory location has changed
   c_wchar_p(139966783348904)
   >>> print(c_s.value)
   Hi, there
   >>> print(s)                # first object is unchanged
   Hello, World
   >>>

Cependant, prenez garde à ne pas en passer à des fonctions qui
prennent en paramètre des pointeurs sur de la mémoire modifiable. S'il
vous faut de la mémoire modifiable, *ctypes* fournit la fonction
"create_string_buffer()" qui en crée de plusieurs façons. L'attribut
"raw" permet d'accéder à (ou de modifier) un bloc mémoire ; l'attribut
"value" permet d'y accéder comme à une chaîne de caractères terminée
par NUL :

   >>> from ctypes import *
   >>> p = create_string_buffer(3)            # create a 3 byte buffer, initialized to NUL bytes
   >>> print(sizeof(p), repr(p.raw))
   3 b'\x00\x00\x00'
   >>> p = create_string_buffer(b"Hello")     # create a buffer containing a NUL terminated string
   >>> print(sizeof(p), repr(p.raw))
   6 b'Hello\x00'
   >>> print(repr(p.value))
   b'Hello'
   >>> p = create_string_buffer(b"Hello", 10) # create a 10 byte buffer
   >>> print(sizeof(p), repr(p.raw))
   10 b'Hello\x00\x00\x00\x00\x00'
   >>> p.value = b"Hi"
   >>> print(sizeof(p), repr(p.raw))
   10 b'Hi\x00lo\x00\x00\x00\x00\x00'
   >>>

The "create_string_buffer()" function replaces the old "c_buffer()"
function (which is still available as an alias).  To create a mutable
memory block containing unicode characters of the C type "wchar_t",
use the "create_unicode_buffer()" function.


Appel de fonctions, suite
-------------------------

*printf* utilise la vraie sortie standard, et non "sys.stdout" ; les
exemples suivants ne fonctionnent donc que dans une invite de commande
et non depuis *IDLE* or *PythonWin* :

   >>> printf = libc.printf
   >>> printf(b"Hello, %s\n", b"World!")
   Hello, World!
   14
   >>> printf(b"Hello, %S\n", "World!")
   Hello, World!
   14
   >>> printf(b"%d bottles of beer\n", 42)
   42 bottles of beer
   19
   >>> printf(b"%f bottles of beer\n", 42.5)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   ctypes.ArgumentError: argument 2: TypeError: Don't know how to convert parameter 2
   >>>

As has been mentioned before, all Python types except integers,
strings, and bytes objects have to be wrapped in their corresponding
"ctypes" type, so that they can be converted to the required C data
type:

   >>> printf(b"An int %d, a double %f\n", 1234, c_double(3.14))
   An int 1234, a double 3.140000
   31
   >>>


Calling variadic functions
--------------------------

On a lot of platforms calling variadic functions through ctypes is
exactly the same as calling functions with a fixed number of
parameters. On some platforms, and in particular ARM64 for Apple
Platforms, the calling convention for variadic functions is different
than that for regular functions.

On those platforms it is required to specify the "argtypes" attribute
for the regular, non-variadic, function arguments:

   libc.printf.argtypes = [ctypes.c_char_p]

Because specifying the attribute does not inhibit portability it is
advised to always specify "argtypes" for all variadic functions.


Appel de fonctions avec des types de données personnalisés
----------------------------------------------------------

You can also customize "ctypes" argument conversion to allow instances
of your own classes be used as function arguments. "ctypes" looks for
an "_as_parameter_" attribute and uses this as the function argument.
The attribute must be an integer, string, bytes, a "ctypes" instance,
or an object with an "_as_parameter_" attribute:

   >>> class Bottles:
   ...     def __init__(self, number):
   ...         self._as_parameter_ = number
   ...
   >>> bottles = Bottles(42)
   >>> printf(b"%d bottles of beer\n", bottles)
   42 bottles of beer
   19
   >>>

If you don't want to store the instance's data in the "_as_parameter_"
instance variable, you could define a "property" which makes the
attribute available on request.


Définition du type des arguments nécessaires (prototypes de fonction)
---------------------------------------------------------------------

It is possible to specify the required argument types of functions
exported from DLLs by setting the "argtypes" attribute.

"argtypes" must be a sequence of C data types (the "printf()" function
is probably not a good example here, because it takes a variable
number and different types of parameters depending on the format
string, on the other hand this is quite handy to experiment with this
feature):

   >>> printf.argtypes = [c_char_p, c_char_p, c_int, c_double]
   >>> printf(b"String '%s', Int %d, Double %f\n", b"Hi", 10, 2.2)
   String 'Hi', Int 10, Double 2.200000
   37
   >>>

Définir un format empêche de passer des arguments de type incompatible
(comme le fait le prototype d'une fonction C) et tente de convertir
les arguments en des types valides :

   >>> printf(b"%d %d %d", 1, 2, 3)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   ctypes.ArgumentError: argument 2: TypeError: 'int' object cannot be interpreted as ctypes.c_char_p
   >>> printf(b"%s %d %f\n", b"X", 2, 3)
   X 2 3.000000
   13
   >>>

If you have defined your own classes which you pass to function calls,
you have to implement a "from_param()" class method for them to be
able to use them in the "argtypes" sequence. The "from_param()" class
method receives the Python object passed to the function call, it
should do a typecheck or whatever is needed to make sure this object
is acceptable, and then return the object itself, its "_as_parameter_"
attribute, or whatever you want to pass as the C function argument in
this case. Again, the result should be an integer, string, bytes, a
"ctypes" instance, or an object with an "_as_parameter_" attribute.


Types de sortie
---------------

By default functions are assumed to return the C int type.  Other
return types can be specified by setting the "restype" attribute of
the function object.

The C prototype of "time()" is "time_t time(time_t *)". Because
"time_t" might be of a different type than the default return type
int, you should specify the "restype" attribute:

   >>> libc.time.restype = c_time_t

The argument types can be specified using "argtypes":

   >>> libc.time.argtypes = (POINTER(c_time_t),)

To call the function with a "NULL" pointer as first argument, use
"None":

   >>> print(libc.time(None))
   1150640792

Here is a more advanced example, it uses the "strchr()" function,
which expects a string pointer and a char, and returns a pointer to a
string:

   >>> strchr = libc.strchr
   >>> strchr(b"abcdef", ord("d"))
   8059983
   >>> strchr.restype = c_char_p    # c_char_p is a pointer to a string
   >>> strchr(b"abcdef", ord("d"))
   b'def'
   >>> print(strchr(b"abcdef", ord("x")))
   None
   >>>

If you want to avoid the "ord("x")" calls above, you can set the
"argtypes" attribute, and the second argument will be converted from a
single character Python bytes object into a C char:

   >>> strchr.restype = c_char_p
   >>> strchr.argtypes = [c_char_p, c_char]
   >>> strchr(b"abcdef", b"d")
   b'def'
   >>> strchr(b"abcdef", b"def")
   Traceback (most recent call last):
   ctypes.ArgumentError: argument 2: TypeError: one character bytes, bytearray or integer expected
   >>> print(strchr(b"abcdef", b"x"))
   None
   >>> strchr(b"abcdef", b"d")
   b'def'
   >>>

You can also use a callable Python object (a function or a class for
example) as the "restype" attribute, if the foreign function returns
an integer.  The callable will be called with the *integer* the C
function returns, and the result of this call will be used as the
result of your function call. This is useful to check for error return
values and automatically raise an exception:

   >>> GetModuleHandle = windll.kernel32.GetModuleHandleA
   >>> def ValidHandle(value):
   ...     if value == 0:
   ...         raise WinError()
   ...     return value
   ...
   >>>
   >>> GetModuleHandle.restype = ValidHandle
   >>> GetModuleHandle(None)
   486539264
   >>> GetModuleHandle("something silly")
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "<stdin>", line 3, in ValidHandle
   OSError: [Errno 126] The specified module could not be found.
   >>>

"WinError" appelle l'API Windows "FormatMessage()" pour obtenir une
représentation de la chaîne de caractères qui correspond au code
d'erreur, et *renvoie* une exception. "WinError" prend en paramètre —
optionnel — le code d'erreur. Si celui-ci n'est pas passé, elle
appelle "GetLastError()" pour le récupérer.

Please note that a much more powerful error checking mechanism is
available through the "errcheck" attribute; see the reference manual
for details.


Passage de pointeurs (passage de paramètres par référence)
----------------------------------------------------------

Il arrive qu'une fonction C du code à interfacer requière un
*pointeur* vers un certain type de donnée en paramètre, typiquement
pour écrire à l'endroit correspondant ou si la donnée est trop grande
pour pouvoir être passée par valeur. Ce mécanisme est appelé *passage
de paramètres par référence*.

"ctypes" exports the "byref()" function which is used to pass
parameters by reference.  The same effect can be achieved with the
"pointer()" function, although "pointer()" does a lot more work since
it constructs a real pointer object, so it is faster to use "byref()"
if you don't need the pointer object in Python itself:

   >>> i = c_int()
   >>> f = c_float()
   >>> s = create_string_buffer(b'\000' * 32)
   >>> print(i.value, f.value, repr(s.value))
   0 0.0 b''
   >>> libc.sscanf(b"1 3.14 Hello", b"%d %f %s",
   ...             byref(i), byref(f), s)
   3
   >>> print(i.value, f.value, repr(s.value))
   1 3.1400001049 b'Hello'
   >>>


Structures et unions
--------------------

Structures and unions must derive from the "Structure" and "Union"
base classes which are defined in the "ctypes" module. Each subclass
must define a "_fields_" attribute.  "_fields_" must be a list of
*2-tuples*, containing a *field name* and a *field type*.

The field type must be a "ctypes" type like "c_int", or any other
derived "ctypes" type: structure, union, array, pointer.

Voici un exemple simple : une structure POINT qui contient deux
entiers *x* et *y* et qui montre également comment instancier une
structure avec le constructeur :

   >>> from ctypes import *
   >>> class POINT(Structure):
   ...     _fields_ = [("x", c_int),
   ...                 ("y", c_int)]
   ...
   >>> point = POINT(10, 20)
   >>> print(point.x, point.y)
   10 20
   >>> point = POINT(y=5)
   >>> print(point.x, point.y)
   0 5
   >>> POINT(1, 2, 3)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   TypeError: too many initializers
   >>>

Il est bien entendu possible de créer des structures plus complexes.
Une structure peut elle-même contenir d'autres structures en prenant
une structure comme type de champ.

Voici une structure RECT qui contient deux POINTs *upperleft* et
*lowerright* :

   >>> class RECT(Structure):
   ...     _fields_ = [("upperleft", POINT),
   ...                 ("lowerright", POINT)]
   ...
   >>> rc = RECT(point)
   >>> print(rc.upperleft.x, rc.upperleft.y)
   0 5
   >>> print(rc.lowerright.x, rc.lowerright.y)
   0 0
   >>>

Une structure encapsulée peut être instanciée par un constructeur de
plusieurs façons :

   >>> r = RECT(POINT(1, 2), POINT(3, 4))
   >>> r = RECT((1, 2), (3, 4))

Field *descriptor*s can be retrieved from the *class*, they are useful
for debugging because they can provide useful information. See
"CField":

   >>> POINT.x
   <ctypes.CField 'x' type=c_int, ofs=0, size=4>
   >>> POINT.y
   <ctypes.CField 'y' type=c_int, ofs=4, size=4>
   >>>

Avertissement:

  "ctypes" does not support passing unions or structures with bit-
  fields to functions by value.  While this may work on 32-bit x86,
  it's not guaranteed by the library to work in the general case.
  Unions and structures with bit-fields should always be passed to
  functions by pointer.


Structure/union layout, alignment and byte order
------------------------------------------------

By default, Structure and Union fields are laid out in the same way
the C compiler does it.  It is possible to override this behavior
entirely by specifying a "_layout_" class attribute in the subclass
definition; see the attribute documentation for details.

It is possible to specify the maximum alignment for the fields and/or
for the structure itself by setting the class attributes "_pack_"
and/or "_align_", respectively. See the attribute documentation for
details.

"ctypes" uses the native byte order for Structures and Unions.  To
build structures with non-native byte order, you can use one of the
"BigEndianStructure", "LittleEndianStructure", "BigEndianUnion", and
"LittleEndianUnion" base classes.  These classes cannot contain
pointer fields.


Champs de bits dans les structures et les unions
------------------------------------------------

It is possible to create structures and unions containing bit fields.
Bit fields are only possible for integer fields, the bit width is
specified as the third item in the "_fields_" tuples:

   >>> class Int(Structure):
   ...     _fields_ = [("first_16", c_int, 16),
   ...                 ("second_16", c_int, 16)]
   ...
   >>> print(Int.first_16)
   <ctypes.CField 'first_16' type=c_int, ofs=0, bit_size=16, bit_offset=0>
   >>> print(Int.second_16)
   <ctypes.CField 'second_16' type=c_int, ofs=0, bit_size=16, bit_offset=16>

It is important to note that bit field allocation and layout in memory
are not defined as a C standard; their implementation is compiler-
specific. By default, Python will attempt to match the behavior of a
"native" compiler for the current platform. See the "_layout_"
attribute for details on the default behavior and how to change it.


Tableaux
--------

Les tableaux sont des séquences qui contiennent un nombre fixe
d'instances du même type.

La meilleure façon de créer des tableaux consiste à multiplier le type
de donnée par un entier positif :

   TenPointsArrayType = POINT * 10

Voici un exemple — un peu artificiel — d'une structure contenant,
entre autres, 4 POINTs :

   >>> from ctypes import *
   >>> class POINT(Structure):
   ...     _fields_ = ("x", c_int), ("y", c_int)
   ...
   >>> class MyStruct(Structure):
   ...     _fields_ = [("a", c_int),
   ...                 ("b", c_float),
   ...                 ("point_array", POINT * 4)]
   >>>
   >>> print(len(MyStruct().point_array))
   4
   >>>

Comme d'habitude, on crée les instances en appelant la classe :

   arr = TenPointsArrayType()
   for pt in arr:
       print(pt.x, pt.y)

Le code précédent affiche une suite de "0 0" car le contenu du tableau
est initialisé avec des zéros.

Des valeurs d'initialisation du bon type peuvent être passées :

   >>> from ctypes import *
   >>> TenIntegers = c_int * 10
   >>> ii = TenIntegers(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
   >>> print(ii)
   <c_long_Array_10 object at 0x...>
   >>> for i in ii: print(i, end=" ")
   ...
   1 2 3 4 5 6 7 8 9 10
   >>>


Pointeurs
---------

Pointer instances are created by calling the "pointer()" function on a
"ctypes" type:

   >>> from ctypes import *
   >>> i = c_int(42)
   >>> pi = pointer(i)
   >>>

Les instances de pointeurs ont un attribut "contents" qui renvoie
l'objet pointé (l'objet "i" ci-dessus) :

   >>> pi.contents
   c_long(42)
   >>>

Note that "ctypes" does not have OOR (original object return), it
constructs a new, equivalent object each time you retrieve an
attribute:

   >>> pi.contents is i
   False
   >>> pi.contents is pi.contents
   False
   >>>

Affecter une autre instance de "c_int" à l'attribut *contents* du
pointeur fait pointer le pointeur vers l'adresse mémoire de cette
nouvelle instance :

   >>> i = c_int(99)
   >>> pi.contents = i
   >>> pi.contents
   c_long(99)
   >>>

Il est possible d'indexer les pointeurs par des entiers :

   >>> pi[0]
   99
   >>>

Affecter à travers un indice change la valeur pointée :

   >>> print(i)
   c_long(99)
   >>> pi[0] = 22
   >>> print(i)
   c_long(22)
   >>>

Si vous êtes sûr de vous, vous pouvez utiliser d'autres valeurs que 0,
comme en C : il est ainsi possible de modifier une zone mémoire de
votre choix. De manière générale cette fonctionnalité ne s'utilise que
sur un pointeur renvoyé par une fonction C, pointeur que vous *savez*
pointer vers un tableau et non sur un seul élément.

Behind the scenes, the "pointer()" function does more than simply
create pointer instances, it has to create pointer *types* first. This
is done with the "POINTER()" function, which accepts any "ctypes"
type, and returns a new type:

   >>> PI = POINTER(c_int)
   >>> PI
   <class 'ctypes.LP_c_long'>
   >>> PI(42)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   TypeError: expected c_long instead of int
   >>> PI(c_int(42))
   <ctypes.LP_c_long object at 0x...>
   >>>

Appeler le pointeur sur type sans arguments crée un pointeur "NULL".
Les pointeurs "NULL" s'évaluent à "False" :

   >>> null_ptr = POINTER(c_int)()
   >>> print(bool(null_ptr))
   False
   >>>

"ctypes" checks for "NULL" when dereferencing pointers (but
dereferencing invalid non-"NULL" pointers would crash Python):

   >>> null_ptr[0]
   Traceback (most recent call last):
       ....
   ValueError: NULL pointer access
   >>>

   >>> null_ptr[0] = 1234
   Traceback (most recent call last):
       ....
   ValueError: NULL pointer access
   >>>


Thread safety without the GIL
-----------------------------

From Python 3.13 onward, the *GIL* can be disabled on the *free-
threaded build*. In ctypes, reads and writes to a single object
concurrently is safe, but not across multiple objects:

      >>> number = c_int(42)
      >>> pointer_a = pointer(number)
      >>> pointer_b = pointer(number)

In the above, it's only safe for one object to read and write to the
address at once if the GIL is disabled. So, "pointer_a" can be shared
and written to across multiple threads, but only if "pointer_b" is not
also attempting to do the same. If this is an issue, consider using a
"threading.Lock" to synchronize access to memory:

      >>> import threading
      >>> lock = threading.Lock()
      >>> # Thread 1
      >>> with lock:
      ...    pointer_a.contents = 24
      >>> # Thread 2
      >>> with lock:
      ...    pointer_b.contents = 42


Conversions de type
-------------------

Usually, ctypes does strict type checking.  This means, if you have
"POINTER(c_int)" in the "argtypes" list of a function or as the type
of a member field in a structure definition, only instances of exactly
the same type are accepted.  There are some exceptions to this rule,
where ctypes accepts other objects.  For example, you can pass
compatible array instances instead of pointer types.  So, for
"POINTER(c_int)", ctypes accepts an array of c_int:

   >>> class Bar(Structure):
   ...     _fields_ = [("count", c_int), ("values", POINTER(c_int))]
   ...
   >>> bar = Bar()
   >>> bar.values = (c_int * 3)(1, 2, 3)
   >>> bar.count = 3
   >>> for i in range(bar.count):
   ...     print(bar.values[i])
   ...
   1
   2
   3
   >>>

In addition, if a function argument is explicitly declared to be a
pointer type (such as "POINTER(c_int)") in "argtypes", an object of
the pointed type ("c_int" in this case) can be passed to the function.
ctypes will apply the required "byref()" conversion in this case
automatically.

Pour mettre un champ de type *POINTER* à "NULL", il faut lui affecter
"None" :

   >>> bar.values = None
   >>>

Sometimes you have instances of incompatible types.  In C, you can
cast one type into another type.  "ctypes" provides a "cast()"
function which can be used in the same way.  The "Bar" structure
defined above accepts "POINTER(c_int)" pointers or "c_int" arrays for
its "values" field, but not instances of other types:

   >>> bar.values = (c_byte * 4)()
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   TypeError: incompatible types, c_byte_Array_4 instance instead of LP_c_long instance
   >>>

C'est là que la fonction "cast()" intervient.

La fonction "cast()" permet de convertir une instance de *ctypes* en
un pointeur vers un type de données *ctypes* différent. "cast()" prend
deux paramètres : un objet *ctypes* qui est, ou qui peut être converti
en, un certain pointeur et un type pointeur de *ctypes*. Elle renvoie
une instance du second argument, qui pointe sur le même bloc mémoire
que le premier argument :

   >>> a = (c_byte * 4)()
   >>> cast(a, POINTER(c_int))
   <ctypes.LP_c_long object at ...>
   >>>

Ainsi, la fonction "cast()" permet de remplir le champ "values" de la
structure "Bar" :

   >>> bar = Bar()
   >>> bar.values = cast((c_byte * 4)(), POINTER(c_int))
   >>> print(bar.values[0])
   0
   >>>


Types incomplets
----------------

Un *type incomplet* est une structure, une union ou un tableau dont
les membres ne sont pas encore définis. C'est l'équivalent d'une
déclaration avancée en C, où la définition est fournie plus tard :

   struct cell; /* forward declaration */

   struct cell {
       char *name;
       struct cell *next;
   };

Une traduction naïve, mais invalide, en code *ctypes* ressemblerait à
ça :

   >>> class cell(Structure):
   ...     _fields_ = [("name", c_char_p),
   ...                 ("next", POINTER(cell))]
   ...
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "<stdin>", line 2, in cell
   NameError: name 'cell' is not defined
   >>>

because the new "class cell" is not available in the class statement
itself. In "ctypes", we can define the "cell" class and set the
"_fields_" attribute later, after the class statement:

   >>> from ctypes import *
   >>> class cell(Structure):
   ...     pass
   ...
   >>> cell._fields_ = [("name", c_char_p),
   ...                  ("next", POINTER(cell))]
   >>>

Essayons. Nous créons deux instances de "cell", les faisons pointer
l'une sur l'autre et enfin nous suivons quelques maillons de la chaîne
de pointeurs :

   >>> c1 = cell()
   >>> c1.name = b"foo"
   >>> c2 = cell()
   >>> c2.name = b"bar"
   >>> c1.next = pointer(c2)
   >>> c2.next = pointer(c1)
   >>> p = c1
   >>> for i in range(8):
   ...     print(p.name, end=" ")
   ...     p = p.next[0]
   ...
   foo bar foo bar foo bar foo bar
   >>>


Fonctions de rappel
-------------------

"ctypes" allows creating C callable function pointers from Python
callables. These are sometimes called *callback functions*.

Tout d'abord, il faut créer une classe pour la fonction de rappel. La
classe connaît la convention d'appel, le type de retour ainsi que le
nombre et le type de paramètres que la fonction accepte.

La fabrique "CFUNCTYPE()" crée un type pour les fonctions de rappel
qui suivent la convention d'appel "cdecl". En Windows, c'est la
fabrique "WINFUNCTYPE()" qui crée un type pour les fonctions de rappel
qui suivent la convention d'appel "stdcall".

Le premier paramètre de ces deux fonctions est le type de retour, et
les suivants sont les types des arguments qu'attend la fonction de
rappel.

I will present an example here which uses the standard C library's
"qsort()" function, that is used to sort items with the help of a
callback function.  "qsort()" will be used to sort an array of
integers:

   >>> IntArray5 = c_int * 5
   >>> ia = IntArray5(5, 1, 7, 33, 99)
   >>> qsort = libc.qsort
   >>> qsort.restype = None
   >>>

"qsort()" must be called with a pointer to the data to sort, the
number of items in the data array, the size of one item, and a pointer
to the comparison function, the callback. The callback will then be
called with two pointers to items, and it must return a negative
integer if the first item is smaller than the second, a zero if they
are equal, and a positive integer otherwise.

Ainsi notre fonction de rappel reçoit des pointeurs vers des entiers
et doit renvoyer un entier. Créons d'abord le "type" pour la fonction
de rappel :

   >>> CMPFUNC = CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
   >>>

Pour commencer, voici une fonction de rappel simple qui affiche les
valeurs qu'on lui passe :

   >>> def py_cmp_func(a, b):
   ...     print("py_cmp_func", a[0], b[0])
   ...     return 0
   ...
   >>> cmp_func = CMPFUNC(py_cmp_func)
   >>>

Résultat :

   >>> qsort(ia, len(ia), sizeof(c_int), cmp_func)
   py_cmp_func 5 1
   py_cmp_func 33 99
   py_cmp_func 7 33
   py_cmp_func 5 7
   py_cmp_func 1 7
   >>>

À présent, comparons pour de vrai les deux entiers et renvoyons un
résultat utile :

   >>> def py_cmp_func(a, b):
   ...     print("py_cmp_func", a[0], b[0])
   ...     return a[0] - b[0]
   ...
   >>>
   >>> qsort(ia, len(ia), sizeof(c_int), CMPFUNC(py_cmp_func))
   py_cmp_func 5 1
   py_cmp_func 33 99
   py_cmp_func 7 33
   py_cmp_func 1 7
   py_cmp_func 5 7
   >>>

Et comme il est facile de le voir, notre tableau est désormais classé
:

   >>> for i in ia: print(i, end=" ")
   ...
   1 5 7 33 99
   >>>

Ces fonctions peuvent aussi être utilisées comme des décorateurs ; il
est donc possible d'écrire :

   >>> @CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
   ... def py_cmp_func(a, b):
   ...     print("py_cmp_func", a[0], b[0])
   ...     return a[0] - b[0]
   ...
   >>> qsort(ia, len(ia), sizeof(c_int), py_cmp_func)
   py_cmp_func 5 1
   py_cmp_func 33 99
   py_cmp_func 7 33
   py_cmp_func 1 7
   py_cmp_func 5 7
   >>>

Note:

  Make sure you keep references to "CFUNCTYPE()" objects as long as
  they are used from C code. "ctypes" doesn't, and if you don't, they
  may be garbage collected, crashing your program when a callback is
  made.Notez aussi que si la fonction de rappel est appelée dans un
  fil d'exécution créé hors de Python (p. ex. par du code externe qui
  appelle la fonction de rappel), *ctypes* crée un nouveau fil Python
  « creux » à chaque fois. Ce comportement est acceptable pour la
  plupart des cas d'utilisation, mais cela implique que les valeurs
  stockées avec "threading.local" ne seront *pas* persistantes d'un
  appel à l'autre, même si les appels proviennent du même fil
  d'exécution C.


Accès aux variables exportées depuis une DLL
--------------------------------------------

Some shared libraries not only export functions, they also export
variables. An example in the Python library itself is the
"Py_Version", Python runtime version number encoded in a single
constant integer.

"ctypes" can access values like this with the "in_dll()" class methods
of the type.  *pythonapi* is a predefined symbol giving access to the
Python C api:

   >>> version = ctypes.c_int.in_dll(ctypes.pythonapi, "Py_Version")
   >>> print(hex(version.value))
   0x30c00a0

Le pointeur "PyImport_FrozenModules" exposé par Python est un autre
exemple complet de l'utilisation de pointeurs.

Citons la documentation :

   This pointer is initialized to point to an array of "_frozen"
   records, terminated by one whose members are all "NULL" or zero.
   When a frozen module is imported, it is searched in this table.
   Third-party code could play tricks with this to provide a
   dynamically created collection of frozen modules.

So manipulating this pointer could even prove useful. To restrict the
example size, we show only how this table can be read with "ctypes":

   >>> from ctypes import *
   >>>
   >>> class struct_frozen(Structure):
   ...     _fields_ = [("name", c_char_p),
   ...                 ("code", POINTER(c_ubyte)),
   ...                 ("size", c_int),
   ...                 ("get_code", POINTER(c_ubyte)),  # Function pointer
   ...                ]
   ...
   >>>

We have defined the "_frozen" data type, so we can get the pointer to
the table:

   >>> FrozenTable = POINTER(struct_frozen)
   >>> table = FrozenTable.in_dll(pythonapi, "_PyImport_FrozenBootstrap")
   >>>

Puisque "table" est un "pointer" vers un tableau d'entrées de
"struct_frozen", il est possible d'itérer dessus, mais il faut être
certain que la boucle se termine, car les pointeurs n'ont pas de
taille. Tôt ou tard, il planterait probablement avec une erreur de
segmentation ou autre, donc mieux vaut sortir de la boucle quand on
lit l'entrée "NULL" :

   >>> for item in table:
   ...     if item.name is None:
   ...         break
   ...     print(item.name.decode("ascii"), item.size)
   ...
   _frozen_importlib 31764
   _frozen_importlib_external 41499
   zipimport 12345
   >>>

Le fait que le standard Python possède un module et un paquet figés
(indiqués par la valeur négative du membre *size*) est peu connu, cela
ne sert qu'aux tests. Essayez avec "import __hello__" par exemple.


Pièges
------

There are some edges in "ctypes" where you might expect something
other than what actually happens.

Examinons l'exemple suivant :

   >>> from ctypes import *
   >>> class POINT(Structure):
   ...     _fields_ = ("x", c_int), ("y", c_int)
   ...
   >>> class RECT(Structure):
   ...     _fields_ = ("a", POINT), ("b", POINT)
   ...
   >>> p1 = POINT(1, 2)
   >>> p2 = POINT(3, 4)
   >>> rc = RECT(p1, p2)
   >>> print(rc.a.x, rc.a.y, rc.b.x, rc.b.y)
   1 2 3 4
   >>> # now swap the two points
   >>> rc.a, rc.b = rc.b, rc.a
   >>> print(rc.a.x, rc.a.y, rc.b.x, rc.b.y)
   3 4 3 4
   >>>

Diantre. On s'attendait certainement à ce que le dernier résultat
affiche "3 4 1 2". Que s'est-il passé ? Les étapes de la ligne "rc.a,
rc.b = rc.b, rc.a" ci-dessus sont les suivantes :

   >>> temp0, temp1 = rc.b, rc.a
   >>> rc.a = temp0
   >>> rc.b = temp1
   >>>

Les objets "temp0" et "temp1" utilisent encore le tampon interne de
l'objet "rc" ci-dessus. Donc exécuter "rc.a = temp0" copie le contenu
du tampon de "temp0" dans celui de "rc". Ce qui, par ricochet, modifie
le contenu de "temp1". Et donc, la dernière affectation, "rc.b =
temp1", n'a pas l'effet escompté.

Gardez en tête qu'accéder au sous-objet depuis une *Structure*, une
*Union* ou un *Array* ne copie *pas* le sous-objet, mais crée un objet
interface qui accède au tampon sous-jacent de l'objet initial.

Un autre exemple de comportement *a priori* inattendu est le suivant :

   >>> s = c_char_p()
   >>> s.value = b"abc def ghi"
   >>> s.value
   b'abc def ghi'
   >>> s.value is s.value
   False
   >>>

Note:

  La valeur d'une instance de "c_char_p" ne peut être initialisée
  qu'avec un octet ou un entier.

Pourquoi cela affiche-t'il "False" ? Les instances *ctypes* sont des
objets qui contiennent un bloc mémoire et des *descriptor* qui donnent
accès au contenu du ce bloc. Stocker un objet Python dans le bloc
mémoire ne stocke pas l'objet même ; seuls ses "contents" le sont.
Accéder au "contents" crée un nouvel objet Python à chaque fois !


Types de données à taille flottante
-----------------------------------

"ctypes" provides some support for variable-sized arrays and
structures.

La fonction "resize()" permet de redimensionner la taille du tampon
mémoire d'un objet *ctypes* existant. Cette fonction prend l'objet
comme premier argument et la taille en octets désirée comme second. La
taille du tampon mémoire ne peut pas être inférieure à celle occupée
par un objet unitaire du type considéré. Une "ValueError" est levée si
c'est le cas :

   >>> short_array = (c_short * 4)()
   >>> print(sizeof(short_array))
   8
   >>> resize(short_array, 4)
   Traceback (most recent call last):
       ...
   ValueError: minimum size is 8
   >>> resize(short_array, 32)
   >>> sizeof(short_array)
   32
   >>> sizeof(type(short_array))
   8
   >>>

Cela dit, comment accéder aux éléments supplémentaires contenus dans
le tableau ? Vu que le type ne connaît que 4 éléments, on obtient une
erreur si l'on accède aux suivants :

   >>> short_array[:]
   [0, 0, 0, 0]
   >>> short_array[7]
   Traceback (most recent call last):
       ...
   IndexError: invalid index
   >>>

Another way to use variable-sized data types with "ctypes" is to use
the dynamic nature of Python, and (re-)define the data type after the
required size is already known, on a case by case basis.


Référence du module
===================


Chargement des bibliothèques partagées
--------------------------------------

There are several ways to load shared libraries into the Python
process.  One way is to instantiate "CDLL" or one of its subclasses:

class ctypes.CDLL(name, mode=DEFAULT_MODE, handle=None, use_errno=False, use_last_error=False, winmode=None)

   Represents a loaded shared library.

   Functions in this library use the standard C calling convention,
   and are assumed to return int. The Python *global interpreter lock*
   is released before calling any function exported by these
   libraries, and reacquired afterwards. For different function
   behavior, use a subclass: "OleDLL", "WinDLL", or "PyDLL".

   If you have an existing "handle" to an already loaded shared
   library, it can be passed as the *handle* argument to wrap the
   opened library in a new "CDLL" object. In this case, *name* is only
   used to set the "_name" attribute, but it may be adjusted and/or
   validated.

   If *handle* is "None", the underlying platform's *dlopen(3)* or
   LoadLibraryExW function is used to load the library into the
   process, and to get a handle to it.

   *name* is the pathname of the shared library to open. If *name*
   does not contain a path separator, the library is found in a
   platform-specific way.

   On Windows, the ".DLL" suffix may be missing. (For details, see
   LoadLibraryExW documentation.) Other platform-specific prefixes and
   suffixes (for example, "lib", ".so", ".dylib", or version numbers)
   must be present in *name*; they are not added automatically. See
   Recherche de bibliothèques partagées for more information.

   On non-Windows systems, *name* can  be "None". In this case,
   "dlopen()" is called with "NULL", which opens the main program as a
   "library". (Some systems do the same is *name* is empty;
   "None"/"NULL" is more portable.)

   CPython implementation detail: Since CPython is linked to "libc", a
   "None" *name* is often used to access the C standard library:

      >>> printf = ctypes.CDLL(None).printf
      >>> printf.argtypes = [ctypes.c_char_p]
      >>> printf(b"hello\n")
      hello
      6

   To access the Python C API, prefer "ctypes.pythonapi" which works
   across platforms.

   Le mode de chargement de la bibliothèque est défini par le
   paramètre *mode*. Pour plus de détails, référez-vous à l'entrée
   *dlopen(3)* du manuel. En Windows, *mode* est ignoré. Sur les
   systèmes POSIX, RTLD_NOW y est toujours ajouté. Ceci n'est pas
   configurable.

   The *use_errno* parameter, when set to true, enables a ctypes
   mechanism that allows accessing the system "errno" error number in
   a safe way. "ctypes" maintains a thread-local copy of the system's
   "errno" variable; if you call foreign functions created with
   "use_errno=True" then the "errno" value before the function call is
   swapped with the ctypes private copy, the same happens immediately
   after the function call.

   La fonction "ctypes.get_errno()" renvoie la valeur de la copie
   privée de *ctypes*. La fonction "ctypes.set_errno()" affecte une
   nouvelle valeur à la copie privée et renvoie l'ancienne valeur.

   The *use_last_error* parameter, when set to true, enables the same
   mechanism for the Windows error code which is managed by the
   "GetLastError()" and "SetLastError()" Windows API functions;
   "ctypes.get_last_error()" and "ctypes.set_last_error()" are used to
   request and change the ctypes private copy of the windows error
   code.

   The *winmode* parameter is used on Windows to specify how the
   library is loaded (since *mode* is ignored). It takes any value
   that is valid for the Win32 API LoadLibraryExW flags parameter.
   When omitted, the default is to use the flags that result in the
   most secure DLL load, which avoids issues such as DLL hijacking.
   Passing the full path to the DLL is the safest way to ensure the
   correct library and dependencies are loaded.

   En Windows, créer une instance de "CDLL" peut échouer, même si une
   DLL du bon nom existe. Quand une des dépendances de la DLL à
   charger ne peut pas être trouvée, une "OSError" est levée avec le
   message *"[WinError 126] The specified module could not be found".*
   Ce message d'erreur ne contient pas le nom de la DLL manquante car
   l'API Windows ne fournit pas cette information. Cela rend l'erreur
   délicate à analyser ; pour la résoudre, il faut lister toutes les
   dépendances de la DLL et trouver celle qui manque en utilisant des
   outils de débogage et de traçage Windows.

   Voir aussi:

     Microsoft DUMPBIN tool -- A tool to find DLL dependents.

   Modifié dans la version 3.8: Ajout du paramètre *winmode*.

   Modifié dans la version 3.12: The *name* parameter can now be a
   *path-like object*.

   Instances of this class have no public methods.  Functions exported
   by the shared library can be accessed as attributes or by index.
   Please note that accessing the function through an attribute caches
   the result and therefore accessing it repeatedly returns the same
   object each time.  On the other hand, accessing it through an index
   returns a new object each time:

      >>> from ctypes import CDLL
      >>> libc = CDLL("libc.so.6")  # On Linux
      >>> libc.time == libc.time
      True
      >>> libc['time'] == libc['time']
      False

   The following public attributes are available. Their name starts
   with an underscore to not clash with exported function names:

   _handle

      Le lien système d'accès à la bibliothèque.

   _name

      Nom de la bibliothèque donné au constructeur.

class ctypes.OleDLL

   See "CDLL", the superclass, for common information.

   Functions in this library use the "stdcall" calling convention, and
   are assumed to return the windows specific "HRESULT" code.
   "HRESULT" values contain information specifying whether the
   function call failed or succeeded, together with additional error
   code.  If the return value signals a failure, an "OSError" is
   automatically raised.

   Disponibilité: Windows

   Modifié dans la version 3.3: "WindowsError" used to be raised,
   which is now an alias of "OSError".

class ctypes.WinDLL

   See "CDLL", the superclass, for common information.

   Functions in these libraries use the "stdcall" calling convention,
   and are assumed to return int by default.

   Disponibilité: Windows

class ctypes.PyDLL

   See "CDLL", the superclass, for common information.

   When functions in this library are called, the Python GIL is *not*
   released during the function call, and after the function execution
   the Python error flag is checked. If the error flag is set, a
   Python exception is raised.

   Thus, this is only useful to call Python C API functions directly.

ctypes.RTLD_GLOBAL

   Valeur possible pour le paramètre *mode*. Vaut zéro sur les plates-
   formes où ce drapeau n'est pas disponible.

ctypes.RTLD_LOCAL

   Valeur possible pour le paramètre *mode*. Vaut *RTLD_GLOBAL* sur
   les plates-formes où ce drapeau n'est pas disponible.

ctypes.DEFAULT_MODE

   Mode de chargement par défaut des bibliothèques partagées. Vaut
   *RTLD_GLOBAL* sur OSX 10.3 et *RTLD_LOCAL* sur les autres systèmes
   d'exploitation.

Shared libraries can also be loaded by using one of the prefabricated
objects, which are instances of the "LibraryLoader" class, either by
calling the "LoadLibrary()" method, or by retrieving the library as
attribute of the loader instance.

class ctypes.LibraryLoader(dlltype)

   Classe pour charger une bibliothèque partagée. *dlltype* doit être
   de type "CDLL", "PyDLL", "WinDLL" ou "OleDLL".

   "__getattr__()" has special behavior: It allows loading a shared
   library by accessing it as attribute of a library loader instance.
   The result is cached, so repeated attribute accesses return the
   same library each time.

   LoadLibrary(name)

      Charge une bibliothèque partagée dans le processus et la
      renvoie. Cette méthode renvoie toujours une nouvelle instance de
      la bibliothèque.

Plusieurs chargeurs sont fournis :

   ctypes.cdll

      Pour créer des instances de "CDLL".

   ctypes.windll

      Creates "WinDLL" instances.

      Disponibilité: Windows

   ctypes.oledll

      Creates "OleDLL" instances.

      Disponibilité: Windows

   ctypes.pydll

      Pour créer des instances de "PyDLL".

   ctypes.pythonapi

      An instance of "PyDLL" that exposes Python C API functions as
      attributes.  Note that all these functions are assumed to return
      C int, which is of course not always the truth, so you have to
      assign the correct "restype" attribute to use these functions.

Charger une bibliothèque à l'aide d'un de ces objets avec en argument
"name", le nom de la bibliothèque (une chaîne de caractères), lève un
évènement d'audit "ctypes.dlopen".

Accéder à une fonction d'une bibliothèque lève un évènement d'audit
"ctypes.dlsym" avec "library" (l'objet bibliothèque) et "name" (le nom
du symbole — une chaîne de caractères ou un entier) comme arguments.

Si seul le lien sur la bibliothèque, et non l'objet, est disponible,
accéder à une fonction lève l'évènement d'audit "ctypes.dlsym/handle"
avec "handle" (le lien vers la bibliothèque) et "name" comme
arguments.


Recherche de bibliothèques partagées
------------------------------------

When programming in a compiled language, shared libraries are accessed
when compiling/linking a program, and when the program is run. The
programmer specifies a short name; the C compiler, linker, and runtime
dynamic library loader then interact in system-specific ways to find
the filename of the library to load.

While the mapping from short names to filenames is not consistently
exposed by platforms, the "ctypes.util" module provides a function,
"find_library()", that attempts to match it. However, as backwards
compatibility concerns make it difficult to adjust its behavior for
new platforms and configurations, the function is *soft deprecated*.

If wrapping a shared library with "ctypes", consider determining the
shared library name at development time, and hardcoding it into the
wrapper module instead of using "find_library()" to locate the library
at runtime. Also consider adding a configuration option or environment
variable to let users select a library to use, and then perhaps use
"find_library()" as a default or fallback.

ctypes.util.find_library(name)

   Try to find a library and return a pathname.

   *name* is the "short" library name without any prefix like "lib",
   suffix like ".so", ".dylib" or version number. (This is the form
   used for the posix linker option "-l".) The result is in a format
   suitable for passing to "CDLL".

   If no library can be found, return "None".

   The exact functionality is system dependent, and is *not
   guaranteed* to match the behavior of the compiler, linker, and
   loader used for (or by) Python. It is recommended to only use this
   function as a default or fallback,

   Soft deprecated since version 3.15: This function is kept for use
   in cases where it works, but not expected to be updated for
   additional platforms and configurations.

On Linux, "find_library()" tries to run external programs
("/sbin/ldconfig", "gcc", "objdump" and "ld") to find the library
file. If the output of these programs does not correspond to the
dynamic linker used by Python, the result of this function may be
misleading.

Modifié dans la version 3.6: Sous Linux, si les autres moyens
échouent, la fonction utilise la variable d'environnement
"LD_LIBRARY_PATH" pour trouver la bibliothèque.

Voici quelques exemples :

   >>> from ctypes.util import find_library
   >>> find_library("m")
   'libm.so.6'
   >>> find_library("c")
   'libc.so.6'
   >>> find_library("bz2")
   'libbz2.so.1.0'
   >>>

On macOS and Android, "find_library()" uses the system's standard
naming schemes and paths to locate the library, and returns a full
pathname if successful:

   >>> from ctypes.util import find_library
   >>> find_library("c")
   '/usr/lib/libc.dylib'
   >>> find_library("m")
   '/usr/lib/libm.dylib'
   >>> find_library("bz2")
   '/usr/lib/libbz2.dylib'
   >>> find_library("AGL")
   '/System/Library/Frameworks/AGL.framework/AGL'
   >>>

On Windows, "find_library()" searches along the system search path,
and returns the full pathname, but since there is no predefined naming
scheme a call like "find_library("c")" will fail and return "None".

ctypes.util.find_msvcrt()

   Returns the filename of the VC runtime library used by Python, and
   by the extension modules.

   If the name of the library cannot be determined, "None" is
   returned. Notably, this will happen for recent versions of the VC
   runtime library, which are not directly loadable.

   If you need to free memory, for example, allocated by an extension
   module with a call to the "free(void *)", it is important that you
   use the function in the same library that allocated the memory.

   Disponibilité: Windows


Listing loaded shared libraries
-------------------------------

When writing code that relies on code loaded from shared libraries, it
can be useful to know which shared libraries have already been loaded
into the current process.

The "ctypes.util" module provides the "dllist()" function, which calls
the different APIs provided by the various platforms to help determine
which shared libraries have already been loaded into the current
process.

The exact output of this function will be system dependent. On most
platforms, the first entry of this list represents the current process
itself, which may be an empty string. For example, on glibc-based
Linux, the return may look like:

   >>> from ctypes.util import dllist
   >>> dllist()
   ['', 'linux-vdso.so.1', '/lib/x86_64-linux-gnu/libm.so.6', '/lib/x86_64-linux-gnu/libc.so.6', ... ]


Fonctions externes
------------------

As explained in the previous section, foreign functions can be
accessed as attributes of loaded shared libraries.  The function
objects created in this way by default accept any number of arguments,
accept any ctypes data instances as arguments, and return the default
result type specified by the library loader.

They are instances of a private local class "_FuncPtr" (not exposed in
"ctypes") which inherits from the private "_CFuncPtr" class:

   >>> import ctypes
   >>> lib = ctypes.CDLL(None)
   >>> issubclass(lib._FuncPtr, ctypes._CFuncPtr)
   True
   >>> lib._FuncPtr is ctypes._CFuncPtr
   False

class ctypes._CFuncPtr

   Classe de base pour les fonctions externes C.

   Une instance de fonction externe est également un type de donnée
   compatible avec le C ; elle représente un pointeur vers une
   fonction.

   Son comportement peut-être personnalisé en réaffectant les
   attributs spécifiques de l'objet représentant la fonction externe.

   restype

      Assign a ctypes type to specify the result type of the foreign
      function. Use "None" for void, a function not returning
      anything.

      It is possible to assign a callable Python object that is not a
      ctypes type, in this case the function is assumed to return a C
      int, and the callable will be called with this integer, allowing
      further processing or error checking.  Using this is deprecated,
      for more flexible post processing or error checking use a ctypes
      data type as "restype" and assign a callable to the "errcheck"
      attribute.

   argtypes

      Fait correspondre le type des arguments que la fonction accepte
      avec un *n*-uplet de types *ctypes*. Les fonctions qui utilisent
      la convention d'appel "stdcall" ne peuvent être appelées qu'avec
      le même nombre d'arguments que la taille du *n*-uplet mais les
      fonctions qui utilisent la convention d'appel C acceptent aussi
      des arguments additionnels non-définis.

      When a foreign function is called, each actual argument is
      passed to the "from_param()" class method of the items in the
      "argtypes" tuple, this method allows adapting the actual
      argument to an object that the foreign function accepts.  For
      example, a "c_char_p" item in the "argtypes" tuple will convert
      a string passed as argument into a bytes object using ctypes
      conversion rules.

      New: It is now possible to put items in argtypes which are not
      ctypes types, but each item must have a "from_param()" method
      which returns a value usable as argument (integer, string,
      ctypes instance).  This allows defining adapters that can adapt
      custom objects as function parameters.

   errcheck

      Définit une fonction Python ou tout autre appelable qui sera
      appelé avec trois arguments ou plus :

      callable(result, func, arguments)

         *result* is what the foreign function returns, as specified
         by the "restype" attribute.

         *func* est l'objet représentant la fonction externe elle-
         même. Cet accesseur permet de réutiliser le même appelable
         pour vérifier le résultat de plusieurs fonctions ou de faire
         des actions supplémentaires après leur exécution.

         *arguments* est le *n*-uplet qui contient les paramètres
         initiaux passés à la fonction, ceci permet de spécialiser le
         comportement des arguments utilisés.

      L'objet renvoyé par cette fonction est celui renvoyé par l'appel
      de la fonction externe, mais il peut aussi vérifier la valeur du
      résultat et lever une exception si l'appel a échoué.

On Windows, when a foreign function call raises a system exception
(for example, due to an access violation), it will be captured and
replaced with a suitable Python exception. Further, an auditing event
"ctypes.set_exception" with argument "code" will be raised, allowing
an audit hook to replace the exception with its own.

Some ways to invoke foreign function calls as well as some of the
functions in this module may raise an auditing event
"ctypes.call_function" with arguments "function pointer" and
"arguments".


Prototypes de fonction
----------------------

Il est aussi possible de créer des fonctions externes en instanciant
des prototypes de fonction. Les prototypes de fonction ressemblent
beaucoup aux prototypes de fonctions en C ; ils décrivent une fonction
(type de retour, type des arguments, convention d'appel) sans préciser
son implémentation. Les fabriques de fonctions prennent en entrée le
type de retour et le type des arguments de la fonction, et peuvent
être utilisées comme des décorateurs-fabrique et ainsi s'appliquer à
des fonctions avec la syntaxe "@décorateur". Ceci est illustré dans la
section Fonctions de rappel.

ctypes.CFUNCTYPE(restype, *argtypes, use_errno=False, use_last_error=False)

   Renvoie un prototype de fonction qui crée des fonctions qui suivent
   la convention d'appel standard C. Les fonctions libèreront le GIL
   lors de leur exécution. Si *use_errno* est vrai, la copie privée
   *ctypes* de la variable système "errno" est échangée avec la vraie
   valeur de "errno" avant et après l'appel ; *use_last_error* a le
   même effet sous Windows.

ctypes.WINFUNCTYPE(restype, *argtypes, use_errno=False, use_last_error=False)

   The returned function prototype creates functions that use the
   "stdcall" calling convention.  The function will release the GIL
   during the call.  *use_errno* and *use_last_error* have the same
   meaning as above.

   Disponibilité: Windows

ctypes.PYFUNCTYPE(restype, *argtypes)

   Renvoie un prototype de fonction qui crée des fonctions qui suivent
   la convention d'appel Python. Les fonctions ne libèreront *pas* le
   GIL lors de leur exécution.

Il y a plusieurs façons d'instancier les prototypes de fonction créés
par ces fabriques, selon le type et le nombre de paramètres de l'appel
:

prototype(address)

   Renvoie une fonction externe sur l'adresse donnée sous la forme
   d'un entier.

prototype(callable)

   Crée une fonction appelable depuis du code C (une fonction de
   rappel) d'un appelable Python donné en paramètre.

prototype(func_spec[, paramflags])

   Renvoie une fonction externe exposée par une bibliothèque partagée.
   *func_spec* est un couple "(nom_ou_indice, bibliothèque)". Le
   premier élément est le nom de la fonction à passer comme une chaîne
   ou bien son indice (dans la table des symboles) à passer comme un
   entier. Le second élément est l'instance de la bibliothèque
   partagée.

prototype(vtbl_index, name[, paramflags[, iid]])

   Renvoie une fonction qui appelle une méthode COM. *vtbl_index* est
   l'indice de la fonction dans la table virtuelle, un petit entier
   positif. *name* est le nom de la méthode COM. *iid* est un pointeur
   optionnel vers l'identificateur de plateforme, qui est utilisé dans
   la remontée d'erreurs étendue.

   If *iid* is not specified, an "OSError" is raised if the COM method
   call fails. If *iid* is specified, a "COMError" is raised instead.

   COM methods use a special calling convention: They require a
   pointer to the COM interface as first argument, in addition to
   those parameters that are specified in the "argtypes" tuple.

   Disponibilité: Windows

Le paramètre optionnel *paramflags* crée une fabrique de fonction
externes avec des fonctionnalités supplémentaires par rapport à celles
décrites ci-dessus.

*paramflags* must be a tuple of the same length as "argtypes".

Chaque élément de ce *n*-uplet contient des informations
supplémentaires sur le paramètre correspondant. Ce doit être aussi un
*n*-uplet, avec un, deux ou trois éléments.

Le premier élément est un entier qui contient une combinaison de
drapeaux qui précisent le sens des paramètres (entrée ou sortie) :

   1
      Paramètre d'entrée.

   2
      Paramètre de sortie. La fonction externe va modifier cette
      valeur.

   4
      Paramètre d'entrée, valant 0 par défaut.

Le deuxième élément (optionnel) est une chaîne de caractères
représentant le nom du paramètre. Si cet élément est donné, la
fonction externe pourra être appelée avec des paramètres nommés.

Le troisième élément (optionnel) est la valeur par défaut du
paramètre.

The following example demonstrates how to wrap the Windows
"MessageBoxW" function so that it supports default parameters and
named arguments. The C declaration from the windows header file is
this:

   WINUSERAPI int WINAPI
   MessageBoxW(
       HWND hWnd,
       LPCWSTR lpText,
       LPCWSTR lpCaption,
       UINT uType);

Here is the wrapping with "ctypes":

   >>> from ctypes import c_int, WINFUNCTYPE, windll
   >>> from ctypes.wintypes import HWND, LPCWSTR, UINT
   >>> prototype = WINFUNCTYPE(c_int, HWND, LPCWSTR, LPCWSTR, UINT)
   >>> paramflags = (1, "hwnd", 0), (1, "text", "Hi"), (1, "caption", "Hello from ctypes"), (1, "flags", 0)
   >>> MessageBox = prototype(("MessageBoxW", windll.user32), paramflags)

La fonction "MessageBox" peut désormais être appelée des manières
suivantes :

   >>> MessageBox()
   >>> MessageBox(text="Spam, spam, spam")
   >>> MessageBox(flags=2, text="foo bar")

L'exemple qui suit traite des paramètres en sortie. La fonction win32
"GetWindowRect" donne les dimensions d'une fenêtre en les copiant dans
une structure "RECT" que l'appelant doit fournir. Sa déclaration en C
est :

   WINUSERAPI BOOL WINAPI
   GetWindowRect(
        HWND hWnd,
        LPRECT lpRect);

Here is the wrapping with "ctypes":

   >>> from ctypes import POINTER, WINFUNCTYPE, windll, WinError
   >>> from ctypes.wintypes import BOOL, HWND, RECT
   >>> prototype = WINFUNCTYPE(BOOL, HWND, POINTER(RECT))
   >>> paramflags = (1, "hwnd"), (2, "lprect")
   >>> GetWindowRect = prototype(("GetWindowRect", windll.user32), paramflags)
   >>>

Les fonctions avec des paramètres en sortie renvoient automatiquement
la valeur du paramètre de sortie s'il n'y en a qu'un seul, ou un
*n*-uplet avec les valeurs de sortie de chaque paramètre s'il y en a
plusieurs. Ici, la fonction *GetWindowRect* renvoie donc une instance
de *RECT* quand elle est appelée.

Output parameters can be combined with the "errcheck" protocol to do
further output processing and error checking.  The win32
"GetWindowRect" api function returns a "BOOL" to signal success or
failure, so this function could do the error checking, and raises an
exception when the api call failed:

   >>> def errcheck(result, func, args):
   ...     if not result:
   ...         raise WinError()
   ...     return args
   ...
   >>> GetWindowRect.errcheck = errcheck
   >>>

If the "errcheck" function returns the argument tuple it receives
unchanged, "ctypes" continues the normal processing it does on the
output parameters.  If you want to return a tuple of window
coordinates instead of a "RECT" instance, you can retrieve the fields
in the function and return them instead, the normal processing will no
longer take place:

   >>> def errcheck(result, func, args):
   ...     if not result:
   ...         raise WinError()
   ...     rc = args[1]
   ...     return rc.left, rc.top, rc.bottom, rc.right
   ...
   >>> GetWindowRect.errcheck = errcheck
   >>>


Fonctions utilitaires
---------------------

ctypes.addressof(obj)

   Returns the address of the memory buffer as integer.  *obj* must be
   an instance of a ctypes type.

   Raises an auditing event "ctypes.addressof" with argument "obj".

ctypes.alignment(obj_or_type)

   Returns the alignment requirements of a ctypes type. *obj_or_type*
   must be a ctypes type or instance.

ctypes.byref(obj[, offset])

   Returns a light-weight pointer to *obj*, which must be an instance
   of a ctypes type.  *offset* defaults to zero, and must be an
   integer that will be added to the internal pointer value.

   "byref(obj, offset)" corresponds to this C code:

      (((char *)&obj) + offset)

   The returned object can only be used as a foreign function call
   parameter. It behaves similar to "pointer(obj)", but the
   construction is a lot faster.

ctypes.CopyComPointer(src, dst)

   Copies a COM pointer from *src* to *dst* and returns the Windows
   specific "HRESULT" value.

   If *src* is not "NULL", its "AddRef" method is called, incrementing
   the reference count.

   In contrast, the reference count of *dst* will not be decremented
   before assigning the new value. Unless *dst* is "NULL", the caller
   is responsible for decrementing the reference count by calling its
   "Release" method when necessary.

   Disponibilité: Windows

   Ajouté dans la version 3.14.

ctypes.cast(obj, type)

   This function is similar to the cast operator in C. It returns a
   new instance of *type* which points to the same memory block as
   *obj*.  *type* must be a pointer type, and *obj* must be an object
   that can be interpreted as a pointer.

ctypes.create_string_buffer(init, size=None)
ctypes.create_string_buffer(size)

   This function creates a mutable character buffer. The returned
   object is a ctypes array of "c_char".

   If *size* is given (and not "None"), it must be an "int". It
   specifies the size of the returned array.

   If the *init* argument is given, it must be "bytes". It is used to
   initialize the array items. Bytes not initialized this way are set
   to zero (NUL).

   If *size* is not given (or if it is "None"), the buffer is made one
   element larger than *init*, effectively adding a NUL terminator.

   If both arguments are given, *size* must not be less than
   "len(init)".

   Avertissement:

     If *size* is equal to "len(init)", a NUL terminator is not added.
     Do not treat such a buffer as a C string.

   Par exemple :

      >>> bytes(create_string_buffer(2))
      b'\x00\x00'
      >>> bytes(create_string_buffer(b'ab'))
      b'ab\x00'
      >>> bytes(create_string_buffer(b'ab', 2))
      b'ab'
      >>> bytes(create_string_buffer(b'ab', 4))
      b'ab\x00\x00'
      >>> bytes(create_string_buffer(b'abcdef', 2))
      Traceback (most recent call last):
         ...
      ValueError: byte string too long

   Raises an auditing event "ctypes.create_string_buffer" with
   arguments "init", "size".

ctypes.create_unicode_buffer(init, size=None)
ctypes.create_unicode_buffer(size)

   This function creates a mutable unicode character buffer. The
   returned object is a ctypes array of "c_wchar".

   The function takes the same arguments as "create_string_buffer()"
   except *init* must be a string and *size* counts "c_wchar".

   Raises an auditing event "ctypes.create_unicode_buffer" with
   arguments "init", "size".

ctypes.DllCanUnloadNow()

   This function is a hook which allows implementing in-process COM
   servers with ctypes.  It is called from the DllCanUnloadNow
   function that the _ctypes extension dll exports.

   Disponibilité: Windows

ctypes.DllGetClassObject()

   This function is a hook which allows implementing in-process COM
   servers with ctypes.  It is called from the DllGetClassObject
   function that the "_ctypes" extension dll exports.

   Disponibilité: Windows

ctypes.util.dllist()

   Try to provide a list of paths of the shared libraries loaded into
   the current process.  These paths are not normalized or processed
   in any way.  The function can raise "OSError" if the underlying
   platform APIs fail. The exact functionality is system dependent.

   On most platforms, the first element of the list represents the
   current executable file. It may be an empty string.

   Disponibilité: Windows, macOS, iOS, glibc, BSD libc, musl

   Ajouté dans la version 3.14.

ctypes.FormatError([code])

   Returns a textual description of the error code *code*.  If no
   error code is specified, the last error code is used by calling the
   Windows API function "GetLastError()".

   Disponibilité: Windows

ctypes.GetLastError()

   Returns the last error code set by Windows in the calling thread.
   This function calls the Windows "GetLastError()" function directly,
   it does not return the ctypes-private copy of the error code.

   Disponibilité: Windows

ctypes.get_errno()

   Returns the current value of the ctypes-private copy of the system
   "errno" variable in the calling thread.

   Raises an auditing event "ctypes.get_errno" with no arguments.

ctypes.get_last_error()

   Returns the current value of the ctypes-private copy of the system
   "LastError" variable in the calling thread.

   Disponibilité: Windows

   Raises an auditing event "ctypes.get_last_error" with no arguments.

ctypes.memmove(dst, src, count)

   Same as the standard C memmove library function: copies *count*
   bytes from *src* to *dst*. *dst* and *src* must be integers or
   ctypes instances that can be converted to pointers.

ctypes.memset(dst, c, count)

   Same as the standard C memset library function: fills the memory
   block at address *dst* with *count* bytes of value *c*. *dst* must
   be an integer specifying an address, or a ctypes instance.

ctypes.POINTER(type, /)

   Create or return a ctypes pointer type. Pointer types are cached
   and reused internally, so calling this function repeatedly is
   cheap. *type* must be a ctypes type.

   **Particularité de l'implémentation CPython :** The resulting
   pointer type is cached in the "__pointer_type__" attribute of
   *type*. It is possible to set this attribute before the first call
   to "POINTER" in order to set a custom pointer type. However, doing
   this is discouraged: manually creating a suitable pointer type is
   difficult without relying on implementation details that may change
   in future Python versions.

ctypes.pointer(obj, /)

   Create a new pointer instance, pointing to *obj*. The returned
   object is of the type "POINTER(type(obj))".

   Note: If you just want to pass a pointer to an object to a foreign
   function call, you should use "byref(obj)" which is much faster.

ctypes.resize(obj, size)

   This function resizes the internal memory buffer of *obj*, which
   must be an instance of a ctypes type.  It is not possible to make
   the buffer smaller than the native size of the objects type, as
   given by "sizeof(type(obj))", but it is possible to enlarge the
   buffer.

ctypes.set_errno(value)

   Set the current value of the ctypes-private copy of the system
   "errno" variable in the calling thread to *value* and return the
   previous value.

   Raises an auditing event "ctypes.set_errno" with argument "errno".

ctypes.set_last_error(value)

   Sets the current value of the ctypes-private copy of the system
   "LastError" variable in the calling thread to *value* and return
   the previous value.

   Disponibilité: Windows

   Raises an auditing event "ctypes.set_last_error" with argument
   "error".

ctypes.sizeof(obj_or_type)

   Returns the size in bytes of a ctypes type or instance memory
   buffer. Does the same as the C "sizeof" operator.

ctypes.string_at(ptr, size=-1)

   Return the byte string at *void *ptr*. If *size* is specified, it
   is used as size, otherwise the string is assumed to be zero-
   terminated.

   Raises an auditing event "ctypes.string_at" with arguments "ptr",
   "size".

ctypes.WinError(code=None, descr=None)

   Creates an instance of "OSError".  If *code* is not specified,
   "GetLastError()" is called to determine the error code. If *descr*
   is not specified, "FormatError()" is called to get a textual
   description of the error.

   Disponibilité: Windows

   Modifié dans la version 3.3: An instance of "WindowsError" used to
   be created, which is now an alias of "OSError".

ctypes.wstring_at(ptr, size=-1)

   Return the wide-character string at *void *ptr*. If *size* is
   specified, it is used as the number of characters of the string,
   otherwise the string is assumed to be zero-terminated.

   Raises an auditing event "ctypes.wstring_at" with arguments "ptr",
   "size".

ctypes.memoryview_at(ptr, size, readonly=False)

   Return a "memoryview" object of length *size* that references
   memory starting at *void *ptr*.

   If *readonly* is true, the returned "memoryview" object can not be
   used to modify the underlying memory. (Changes made by other means
   will still be reflected in the returned object.)

   This function is similar to "string_at()" with the key difference
   of not making a copy of the specified memory. It is a semantically
   equivalent (but more efficient) alternative to "memoryview((c_byte
   * size).from_address(ptr))". (While "from_address()" only takes
   integers, *ptr* can also be given as a "ctypes.POINTER" or a
   "byref()" object.)

   Raises an auditing event "ctypes.memoryview_at" with arguments
   "address", "size", "readonly".

   Ajouté dans la version 3.14.


Types de données
----------------

class ctypes._CData

   This non-public class is the common base class of all ctypes data
   types. Among other things, all ctypes type instances contain a
   memory block that hold C compatible data; the address of the memory
   block is returned by the "addressof()" helper function. Another
   instance variable is exposed as "_objects"; this contains other
   Python objects that need to be kept alive in case the memory block
   contains pointers.

   Common methods of ctypes data types, these are all class methods
   (to be exact, they are methods of the *metaclass*):

   from_buffer(source[, offset])

      This method returns a ctypes instance that shares the buffer of
      the *source* object.  The *source* object must support the
      writeable buffer interface.  The optional *offset* parameter
      specifies an offset into the source buffer in bytes; the default
      is zero.  If the source buffer is not large enough a
      "ValueError" is raised.

      Raises an auditing event "ctypes.cdata/buffer" with arguments
      "pointer", "size", "offset".

   from_buffer_copy(source[, offset])

      This method creates a ctypes instance, copying the buffer from
      the *source* object buffer which must be readable.  The optional
      *offset* parameter specifies an offset into the source buffer in
      bytes; the default is zero.  If the source buffer is not large
      enough a "ValueError" is raised.

      Raises an auditing event "ctypes.cdata/buffer" with arguments
      "pointer", "size", "offset".

   from_address(address)

      This method returns a ctypes type instance using the memory
      specified by *address* which must be an integer.

      This method, and others that indirectly call this method, raises
      an auditing event "ctypes.cdata" with argument "address".

   from_param(obj)

      This method adapts *obj* to a ctypes type.  It is called with
      the actual object used in a foreign function call when the type
      is present in the foreign function's "argtypes" tuple; it must
      return an object that can be used as a function call parameter.

      All ctypes data types have a default implementation of this
      classmethod that normally returns *obj* if that is an instance
      of the type.  Some types accept other objects as well.

   in_dll(library, name)

      This method returns a ctypes type instance exported by a shared
      library. *name* is the name of the symbol that exports the data,
      *library* is the loaded shared library.

   Common class variables of ctypes data types:

   __pointer_type__

      The pointer type that was created by calling "POINTER()" for
      corresponding ctypes data type. If a pointer type was not yet
      created, the attribute is missing.

      Ajouté dans la version 3.14.

   Common instance variables of ctypes data types:

   _b_base_

      Sometimes ctypes data instances do not own the memory block they
      contain, instead they share part of the memory block of a base
      object.  The "_b_base_" read-only member is the root ctypes
      object that owns the memory block.

   _b_needsfree_

      This read-only variable is true when the ctypes data instance
      has allocated the memory block itself, false otherwise.

   _objects

      This member is either "None" or a dictionary containing Python
      objects that need to be kept alive so that the memory block
      contents is kept valid.  This object is only exposed for
      debugging; never modify the contents of this dictionary.


Types de données de base
------------------------

class ctypes._SimpleCData

   This non-public class is the base class of all fundamental ctypes
   data types. It is mentioned here because it contains the common
   attributes of the fundamental ctypes data types.  "_SimpleCData" is
   a subclass of "_CData", so it inherits their methods and
   attributes. ctypes data types that are not and do not contain
   pointers can now be pickled.

   Instances have a single attribute:

   value

      This attribute contains the actual value of the instance. For
      integer and pointer types, it is an integer, for character
      types, it is a single character bytes object or string, for
      character pointer types it is a Python bytes object or string.

      When the "value" attribute is retrieved from a ctypes instance,
      usually a new object is returned each time.  "ctypes" does *not*
      implement original object return, always a new object is
      constructed.  The same is true for all other ctypes object
      instances.

   Each subclass has a class attribute:

   _type_

      Class attribute that contains an internal type code, as a
      string. See Types de données de base for a summary.

      Types marked * in the summary may be (or always are) aliases of
      a different "_SimpleCData" subclass, and will not necessarily
      use the listed type code. For example, if the platform's long,
      long long and time_t C types are the same, then "c_long",
      "c_longlong" and "c_time_t" all refer to a single class,
      "c_long", whose "_type_" code is "'l'". The "'L'" code will be
      unused.

      Voir aussi:

        The "array" and struct modules, as well as third-party modules
        like numpy, use similar -- but slightly different -- type
        codes.

Fundamental data types, when returned as foreign function call
results, or, for example, by retrieving structure field members or
array items, are transparently converted to native Python types.  In
other words, if a foreign function has a "restype" of "c_char_p", you
will always receive a Python bytes object, *not* a "c_char_p"
instance.

Subclasses of fundamental data types do *not* inherit this behavior.
So, if a foreign functions "restype" is a subclass of "c_void_p", you
will receive an instance of this subclass from the function call. Of
course, you can get the value of the pointer by accessing the "value"
attribute.

These are the fundamental ctypes data types:

class ctypes.c_byte

   Represents the C signed char datatype, and interprets the value as
   small integer.  The constructor accepts an optional integer
   initializer; no overflow checking is done.

class ctypes.c_char

   Represents the C char datatype, and interprets the value as a
   single character.  The constructor accepts an optional string
   initializer, the length of the string must be exactly one
   character.

class ctypes.c_char_p

   Represents the C char* datatype when it points to a zero-terminated
   string.  For a general character pointer that may also point to
   binary data, "POINTER(c_char)" must be used.  The constructor
   accepts an integer address, or a bytes object.

class ctypes.c_double

   Represents the C double datatype.  The constructor accepts an
   optional float initializer.

class ctypes.c_longdouble

   Represents the C long double datatype.  The constructor accepts an
   optional float initializer.  On platforms where "sizeof(long
   double) == sizeof(double)" it is an alias to "c_double".

class ctypes.c_float

   Represents the C float datatype.  The constructor accepts an
   optional float initializer.

class ctypes.c_double_complex

   Represents the C double complex datatype, if available.  The
   constructor accepts an optional "complex" initializer.

   Ajouté dans la version 3.14.

class ctypes.c_float_complex

   Represents the C float complex datatype, if available.  The
   constructor accepts an optional "complex" initializer.

   Ajouté dans la version 3.14.

class ctypes.c_longdouble_complex

   Represents the C long double complex datatype, if available.  The
   constructor accepts an optional "complex" initializer.

   Ajouté dans la version 3.14.

class ctypes.c_int

   Represents the C signed int datatype.  The constructor accepts an
   optional integer initializer; no overflow checking is done.  On
   platforms where "sizeof(int) == sizeof(long)" it is an alias to
   "c_long".

class ctypes.c_int8

   Represents the C 8-bit signed int datatype.  It is an alias for
   "c_byte".

class ctypes.c_int16

   Represents the C 16-bit signed int datatype.  Usually an alias for
   "c_short".

class ctypes.c_int32

   Represents the C 32-bit signed int datatype.  Usually an alias for
   "c_int".

class ctypes.c_int64

   Represents the C 64-bit signed int datatype.  Usually an alias for
   "c_longlong".

class ctypes.c_long

   Represents the C signed long datatype.  The constructor accepts an
   optional integer initializer; no overflow checking is done.

class ctypes.c_longlong

   Represents the C signed long long datatype.  The constructor
   accepts an optional integer initializer; no overflow checking is
   done. On platforms where "sizeof(long long) == sizeof(long)" it is
   an alias to "c_long".

class ctypes.c_short

   Represents the C signed short datatype.  The constructor accepts an
   optional integer initializer; no overflow checking is done.

class ctypes.c_size_t

   Represents the C "size_t" datatype. Usually an alias for another
   unsigned integer type.

class ctypes.c_ssize_t

   Represents the "Py_ssize_t" datatype. This is a signed version of
   "size_t"; that is, the POSIX "ssize_t" type. Usually an alias for
   another integer type.

   Ajouté dans la version 3.2.

class ctypes.c_time_t

   Represents the C "time_t" datatype. Usually an alias for another
   integer type.

   Ajouté dans la version 3.12.

class ctypes.c_ubyte

   Represents the C unsigned char datatype, it interprets the value as
   small integer.  The constructor accepts an optional integer
   initializer; no overflow checking is done.

class ctypes.c_uint

   Represents the C unsigned int datatype.  The constructor accepts an
   optional integer initializer; no overflow checking is done.  On
   platforms where "sizeof(int) == sizeof(long)" it is an alias for
   "c_ulong".

class ctypes.c_uint8

   Represents the C 8-bit unsigned int datatype.  It is an alias for
   "c_ubyte".

class ctypes.c_uint16

   Represents the C 16-bit unsigned int datatype.  Usually an alias
   for "c_ushort".

class ctypes.c_uint32

   Represents the C 32-bit unsigned int datatype.  Usually an alias
   for "c_uint".

class ctypes.c_uint64

   Represents the C 64-bit unsigned int datatype.  Usually an alias
   for "c_ulonglong".

class ctypes.c_ulong

   Represents the C unsigned long datatype.  The constructor accepts
   an optional integer initializer; no overflow checking is done.

class ctypes.c_ulonglong

   Represents the C unsigned long long datatype.  The constructor
   accepts an optional integer initializer; no overflow checking is
   done. On platforms where "sizeof(long long) == sizeof(long)" it is
   an alias to "c_long".

class ctypes.c_ushort

   Represents the C unsigned short datatype.  The constructor accepts
   an optional integer initializer; no overflow checking is done.

class ctypes.c_void_p

   Represents the C void* type.  The value is represented as integer.
   The constructor accepts an optional integer initializer.

class ctypes.c_wchar

   Represents the C "wchar_t" datatype, and interprets the value as a
   single character unicode string.  The constructor accepts an
   optional string initializer, the length of the string must be
   exactly one character.

class ctypes.c_wchar_p

   Represents the C wchar_t* datatype, which must be a pointer to a
   zero-terminated wide character string.  The constructor accepts an
   integer address, or a string.

class ctypes.c_bool

   Represent the C bool datatype (more accurately, _Bool from C99).
   Its value can be "True" or "False", and the constructor accepts any
   object that has a truth value.

class ctypes.HRESULT

   Represents a "HRESULT" value, which contains success or error
   information for a function or method call.

   Disponibilité: Windows

class ctypes.py_object

   Represents the C PyObject* datatype.  Calling this without an
   argument creates a "NULL" PyObject* pointer.

   Modifié dans la version 3.14: "py_object" is now a *generic type*.

The "ctypes.wintypes" module provides quite some other Windows
specific data types, for example "HWND", "WPARAM", "VARIANT_BOOL" or
"DWORD". Some useful structures like "MSG" or "RECT" are also defined.


Types de données dérivés de Structure
-------------------------------------

class ctypes.Union(*args, **kw)

   Abstract base class for unions in native byte order.

   Unions share common attributes and behavior with structures; see
   "Structure" documentation for details.

class ctypes.BigEndianUnion(*args, **kw)

   Abstract base class for unions in *big endian* byte order.

   Ajouté dans la version 3.11.

class ctypes.LittleEndianUnion(*args, **kw)

   Abstract base class for unions in *little endian* byte order.

   Ajouté dans la version 3.11.

class ctypes.BigEndianStructure(*args, **kw)

   Abstract base class for structures in *big endian* byte order.

class ctypes.LittleEndianStructure(*args, **kw)

   Abstract base class for structures in *little endian* byte order.

Structures and unions with non-native byte order cannot contain
pointer type fields, or any other data types containing pointer type
fields.

class ctypes.Structure(*args, **kw)

   Abstract base class for structures in *native* byte order.

   Concrete structure and union types must be created by subclassing
   one of these types, and at least define a "_fields_" class
   variable. "ctypes" will create *descriptor*s which allow reading
   and writing the fields by direct attribute accesses.  These are the

   _fields_

      A sequence defining the structure fields.  The items must be
      2-tuples or 3-tuples.  The first item is the name of the field,
      the second item specifies the type of the field; it can be any
      ctypes data type.

      For integer type fields like "c_int", a third optional item can
      be given.  It must be a small positive integer defining the bit
      width of the field.

      Field names must be unique within one structure or union.  This
      is not checked, only one field can be accessed when names are
      repeated.

      It is possible to define the "_fields_" class variable *after*
      the class statement that defines the Structure subclass, this
      allows creating data types that directly or indirectly reference
      themselves:

         class List(Structure):
             pass
         List._fields_ = [("pnext", POINTER(List)),
                          ...
                         ]

      The "_fields_" class variable can only be set once. Later
      assignments will raise an "AttributeError".

      Additionally, the "_fields_" class variable must be defined
      before the structure or union type is first used: an instance or
      subclass is created, "sizeof()" is called on it, and so on.
      Later assignments to "_fields_" will raise an "AttributeError".
      If "_fields_" has not been set before such use, the structure or
      union will have no own fields, as if "_fields_" was empty.

      Sub-subclasses of structure types inherit the fields of the base
      class plus the "_fields_" defined in the sub-subclass, if any.

   _pack_

      An optional small integer that allows overriding the alignment
      of structure fields in the instance.

      This is only implemented for the MSVC-compatible memory layout
      (see "_layout_").

      Setting "_pack_" to 0 is the same as not setting it at all.
      Otherwise, the value must be a positive power of two. The effect
      is equivalent to "#pragma pack(N)" in C, except "ctypes" may
      allow larger *n* than what the compiler accepts.

      "_pack_" must already be defined when "_fields_" is assigned,
      otherwise it will have no effect.

      Deprecated since version 3.14, will be removed in version 3.19:
      For historical reasons, if "_pack_" is non-zero, the MSVC-
      compatible layout will be used by default. On non-Windows
      platforms, this default is deprecated and is slated to become an
      error in Python 3.19. If it is intended, set "_layout_" to
      "'ms'" explicitly.

   _align_

      An optional small integer that allows increasing the alignment
      of the structure when being packed or unpacked to/from memory.

      The value must not be negative. The effect is equivalent to
      "__attribute__((aligned(N)))" on GCC or "#pragma align(N)" on
      MSVC, except "ctypes" may allow values that the compiler would
      reject.

      "_align_" can only *increase* a structure's alignment
      requirements. Setting it to 0 or 1 has no effect.

      Using values that are not powers of two is discouraged and may
      lead to surprising behavior.

      "_align_" must already be defined when "_fields_" is assigned,
      otherwise it will have no effect.

      Ajouté dans la version 3.13.

   _layout_

      An optional string naming the struct/union layout. It can
      currently be set to:

      * ""ms"": the layout used by the Microsoft compiler (MSVC). On
        GCC and Clang, this layout can be selected with
        "__attribute__((ms_struct))".

      * ""gcc-sysv"": the layout used by GCC with the System V or
        “SysV-like” data model, as used on Linux and macOS. With this
        layout, "_pack_" must be unset or zero.

      If not set explicitly, "ctypes" will use a default that matches
      the platform conventions. This default may change in future
      Python releases (for example, when a new platform gains official
      support, or when a difference between similar platforms is
      found). Currently the default will be:

      * On Windows: ""ms""

      * When "_pack_" is specified: ""ms"". (This is deprecated; see
        "_pack_" documentation.)

      * Otherwise: ""gcc-sysv""

      "_layout_" must already be defined when "_fields_" is assigned,
      otherwise it will have no effect.

      Ajouté dans la version 3.14.

   _anonymous_

      An optional sequence that lists the names of unnamed (anonymous)
      fields. "_anonymous_" must be already defined when "_fields_" is
      assigned, otherwise it will have no effect.

      The fields listed in this variable must be structure or union
      type fields. "ctypes" will create descriptors in the structure
      type that allows accessing the nested fields directly, without
      the need to create the structure or union field.

      Here is an example type (Windows):

         class _U(Union):
             _fields_ = [("lptdesc", POINTER(TYPEDESC)),
                         ("lpadesc", POINTER(ARRAYDESC)),
                         ("hreftype", HREFTYPE)]

         class TYPEDESC(Structure):
             _anonymous_ = ("u",)
             _fields_ = [("u", _U),
                         ("vt", VARTYPE)]

      The "TYPEDESC" structure describes a COM data type, the "vt"
      field specifies which one of the union fields is valid.  Since
      the "u" field is defined as anonymous field, it is now possible
      to access the members directly off the TYPEDESC instance.
      "td.lptdesc" and "td.u.lptdesc" are equivalent, but the former
      is faster since it does not need to create a temporary union
      instance:

         td = TYPEDESC()
         td.vt = VT_PTR
         td.lptdesc = POINTER(some_type)
         td.u.lptdesc = POINTER(some_type)

   It is possible to define sub-subclasses of structures, they inherit
   the fields of the base class.  If the subclass definition has a
   separate "_fields_" variable, the fields specified in this are
   appended to the fields of the base class.

   Structure and union constructors accept both positional and keyword
   arguments.  Positional arguments are used to initialize member
   fields in the same order as they are appear in "_fields_".  Keyword
   arguments in the constructor are interpreted as attribute
   assignments, so they will initialize "_fields_" with the same name,
   or create new attributes for names not present in "_fields_".

class ctypes.CField(*args, **kw)

   Descriptor for fields of a "Structure" and "Union". For example:

      >>> class Color(Structure):
      ...     _fields_ = (
      ...         ('red', c_uint8),
      ...         ('green', c_uint8),
      ...         ('blue', c_uint8),
      ...         ('intense', c_bool, 1),
      ...         ('blinking', c_bool, 1),
      ...    )
      ...
      >>> Color.red
      <ctypes.CField 'red' type=c_ubyte, ofs=0, size=1>
      >>> Color.green.type
      <class 'ctypes.c_ubyte'>
      >>> Color.blue.byte_offset
      2
      >>> Color.intense
      <ctypes.CField 'intense' type=c_bool, ofs=3, bit_size=1, bit_offset=0>
      >>> Color.blinking.bit_offset
      1

   All attributes are read-only.

   "CField" objects are created via "_fields_"; do not instantiate the
   class directly.

   Ajouté dans la version 3.14: Previously, descriptors only had
   "offset" and "size" attributes and a readable string
   representation; the "CField" class was not available directly.

   name

      Name of the field, as a string.

   type

      Type of the field, as a ctypes class.

   offset
   byte_offset

      Offset of the field, in bytes.

      For bitfields, this is the offset of the underlying byte-aligned
      *storage unit*; see "bit_offset".

   byte_size

      Size of the field, in bytes.

      For bitfields, this is the size of the underlying *storage
      unit*. Typically, it has the same size as the bitfield's type.

   size

      For non-bitfields, equivalent to "byte_size".

      For bitfields, this contains a backwards-compatible bit-packed
      value that combines "bit_size" and "bit_offset". Prefer using
      the explicit attributes instead.

   is_bitfield

      True if this is a bitfield.

   bit_offset
   bit_size

      The location of a bitfield within its *storage unit*, that is,
      within "byte_size" bytes of memory starting at "byte_offset".

      To get the field's value, read the storage unit as an integer,
      shift left by "bit_offset" and take the "bit_size" least
      significant bits.

      For non-bitfields, "bit_offset" is zero and "bit_size" is equal
      to "byte_size * 8".

   is_anonymous

      True if this field is anonymous, that is, it contains nested
      sub-fields that should be merged into a containing structure or
      union.


Tableaux et pointeurs
---------------------

class ctypes.Array(*args)

   Classe de base abstraite pour les *arrays*.

   The recommended way to create concrete array types is by
   multiplying any "ctypes" data type with a non-negative integer.
   Alternatively, you can subclass this type and define "_length_" and
   "_type_" class variables. Array elements can be read and written
   using standard subscript and slice accesses; for slice reads, the
   resulting object is *not* itself an "Array".

   _length_

      A positive integer specifying the number of elements in the
      array. Out-of-range subscripts result in an "IndexError". Will
      be returned by "len()".

   _type_

      Spécifie le type de chaque élément de l'*array*.

   Array subclass constructors accept positional arguments, used to
   initialize the elements in order.

ctypes.ARRAY(type, length)

   Create an array. Equivalent to "type * length", where *type* is a
   "ctypes" data type and *length* an integer.

   Soft deprecated since version 3.14: In favor of multiplication.

class ctypes._Pointer

   Private, abstract base class for pointers.

   Concrete pointer types are created by calling "POINTER()" with the
   type that will be pointed to; this is done automatically by
   "pointer()".

   If a pointer points to an array, its elements can be read and
   written using standard subscript and slice accesses.  Pointer
   objects have no size, so "len()" will raise "TypeError".  Negative
   subscripts will read from the memory *before* the pointer (as in
   C), and out-of-range subscripts will probably crash with an access
   violation (if you're lucky).

   _type_

      Specifies the type pointed to.

   contents

      Returns the object to which to pointer points.  Assigning to
      this attribute changes the pointer to point to the assigned
      object.


Exceptions
----------

exception ctypes.ArgumentError

   Exception levée quand un appel à la fonction externe ne peut pas
   convertir un des arguments qu'elle a reçus.

exception ctypes.COMError(hresult, text, details)

   This exception is raised when a COM method call failed.

   hresult

      The integer value representing the error code.

   text

      The error message.

   details

      The 5-tuple "(descr, source, helpfile, helpcontext, progid)".

      *descr* is the textual description.  *source* is the language-
      dependent "ProgID" for the class or application that raised the
      error.  *helpfile* is the path of the help file.  *helpcontext*
      is the help context identifier.  *progid* is the "ProgID" of the
      interface that defined the error.

   Disponibilité: Windows

   Ajouté dans la version 3.14.
