Objetos enteros

Todos los enteros se implementan como objetos enteros «largos» (long) de tamaño arbitrario.

En caso de error, la mayoría de las API PyLong_As* retornan (tipo de retorno) -1 que no se puede distinguir de un número. Use PyErr_Occurred() para desambiguar.

type PyLongObject
Part of the Limited API (as an opaque struct).

Este subtipo de PyObject representa un objeto entero de Python.

PyTypeObject PyLong_Type
Part of the Stable ABI.

Esta instancia de PyTypeObject representa el tipo entero de Python. Este es el mismo objeto que int en la capa de Python.

int PyLong_Check(PyObject *p)

Retorna verdadero si su argumento es un PyLongObject o un subtipo de PyLongObject. Esta función siempre finaliza con éxito.

int PyLong_CheckExact(PyObject *p)

Retorna verdadero si su argumento es un PyLongObject, pero no un subtipo de PyLongObject. Esta función siempre finaliza con éxito.

PyObject *PyLong_FromLong(long v)
Return value: New reference. Part of the Stable ABI.

Retorna un objeto PyLongObject nuevo desde v, o NULL en caso de error.

The current implementation keeps an array of integer objects for all integers between -5 and 256. When you create an int in that range you actually just get back a reference to the existing object.

PyObject *PyLong_FromUnsignedLong(unsigned long v)
Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C unsigned long, or NULL on failure.

PyObject *PyLong_FromSsize_t(Py_ssize_t v)
Return value: New reference. Part of the Stable ABI.

Retorna un objeto PyLongObject nuevo desde un C Py_ssize_t, o NULL en caso de error.

PyObject *PyLong_FromSize_t(size_t v)
Return value: New reference. Part of the Stable ABI.

Retorna un objeto PyLongObject nuevo desde un C size_t, o NULL en caso de error.

PyObject *PyLong_FromLongLong(long long v)
Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C long long, or NULL on failure.

PyObject *PyLong_FromUnsignedLongLong(unsigned long long v)
Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C unsigned long long, or NULL on failure.

PyObject *PyLong_FromDouble(double v)
Return value: New reference. Part of the Stable ABI.

Retorna un nuevo objeto PyLongObject de la parte entera de v, o NULL en caso de error.

PyObject *PyLong_FromString(const char *str, char **pend, int base)
Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject based on the string value in str, which is interpreted according to the radix in base, or NULL on failure. If pend is non-NULL, *pend will point to the end of str on success or to the first character that could not be processed on error. If base is 0, str is interpreted using the Literales enteros definition; in this case, leading zeros in a non-zero decimal number raises a ValueError. If base is not 0, it must be between 2 and 36, inclusive. Leading and trailing whitespace and single underscores after a base specifier and between digits are ignored. If there are no digits or str is not NULL-terminated following the digits and trailing whitespace, ValueError will be raised.

Ver también

Python methods int.to_bytes() and int.from_bytes() to convert a PyLongObject to/from an array of bytes in base 256. You can call those from C using PyObject_CallMethod().

PyObject *PyLong_FromUnicodeObject(PyObject *u, int base)
Return value: New reference.

Convierte una secuencia de dígitos Unicode en la cadena de caracteres u en un valor entero de Python.

Added in version 3.3.

PyObject *PyLong_FromVoidPtr(void *p)
Return value: New reference. Part of the Stable ABI.

Crea un entero de Python desde el puntero p. El valor del puntero se puede recuperar del valor resultante usando PyLong_AsVoidPtr().

PyObject *PyLong_FromNativeBytes(const void *buffer, size_t n_bytes, int flags)

Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as a two’s-complement signed number.

flags are as for PyLong_AsNativeBytes(). Passing -1 will select the native endian that CPython was compiled with and assume that the most-significant bit is a sign bit. Passing Py_ASNATIVEBYTES_UNSIGNED_BUFFER will produce the same result as calling PyLong_FromUnsignedNativeBytes(). Other flags are ignored.

Added in version 3.13.

PyObject *PyLong_FromUnsignedNativeBytes(const void *buffer, size_t n_bytes, int flags)

Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as an unsigned number.

flags are as for PyLong_AsNativeBytes(). Passing -1 will select the native endian that CPython was compiled with and assume that the most-significant bit is not a sign bit. Flags other than endian are ignored.

Added in version 3.13.

long PyLong_AsLong(PyObject *obj)
Part of the Stable ABI.

Return a C long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

Raise OverflowError if the value of obj is out of range for a long.

Retorna -1 en caso de error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

int PyLong_AsInt(PyObject *obj)
Part of the Stable ABI since version 3.13.

Similar to PyLong_AsLong(), but store the result in a C int instead of a C long.

Added in version 3.13.

long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)
Part of the Stable ABI.

Return a C long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is greater than LONG_MAX or less than LONG_MIN, set *overflow to 1 or -1, respectively, and return -1; otherwise, set *overflow to 0. If any other exception occurs set *overflow to 0 and return -1 as usual.

Retorna -1 en caso de error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

long long PyLong_AsLongLong(PyObject *obj)
Part of the Stable ABI.

Return a C long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

Raise OverflowError if the value of obj is out of range for a long long.

Retorna -1 en caso de error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

long long PyLong_AsLongLongAndOverflow(PyObject *obj, int *overflow)
Part of the Stable ABI.

Return a C long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is greater than LLONG_MAX or less than LLONG_MIN, set *overflow to 1 or -1, respectively, and return -1; otherwise, set *overflow to 0. If any other exception occurs set *overflow to 0 and return -1 as usual.

Retorna -1 en caso de error. Use PyErr_Occurred() para desambiguar.

Added in version 3.2.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
Part of the Stable ABI.

Retorna una representación de C Py_ssize_t de pylong. pylong debe ser una instancia de PyLongObject.

Lanza OverflowError si el valor de pylong está fuera de rango para un Py_ssize_t.

Retorna -1 en caso de error. Use PyErr_Occurred() para desambiguar.

unsigned long PyLong_AsUnsignedLong(PyObject *pylong)
Part of the Stable ABI.

Return a C unsigned long representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a unsigned long.

Retorna (unsigned long)-1 en caso de error. Use PyErr_Occurred() para desambiguar.

size_t PyLong_AsSize_t(PyObject *pylong)
Part of the Stable ABI.

Retorna una representación de C size_t de pylong. pylong debe ser una instancia de PyLongObject.

Lanza OverflowError si el valor de pylong está fuera de rango para un size_t.

Retorna (size_t) -1 en caso de error. Use PyErr_Occurred() para desambiguar.

unsigned long long PyLong_AsUnsignedLongLong(PyObject *pylong)
Part of the Stable ABI.

Return a C unsigned long long representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for an unsigned long long.

Retorna (unsigned long long) -1 en caso de error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.1: Ahora un pylong negativo lanza un OverflowError, no TypeError.

unsigned long PyLong_AsUnsignedLongMask(PyObject *obj)
Part of the Stable ABI.

Return a C unsigned long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is out of range for an unsigned long, return the reduction of that value modulo ULONG_MAX + 1.

Retorna (unsigned long)-1 en caso de error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

unsigned long long PyLong_AsUnsignedLongLongMask(PyObject *obj)
Part of the Stable ABI.

Return a C unsigned long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is out of range for an unsigned long long, return the reduction of that value modulo ULLONG_MAX + 1.

Retorna (unsigned long long) -1 por error. Use PyErr_Occurred() para desambiguar.

Distinto en la versión 3.8: Use __index__() if available.

Distinto en la versión 3.10: This function will no longer use __int__().

double PyLong_AsDouble(PyObject *pylong)
Part of the Stable ABI.

Return a C double representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a double.

Retorna -1.0 en caso de error. Use PyErr_Occurred() para desambiguar.

void *PyLong_AsVoidPtr(PyObject *pylong)
Part of the Stable ABI.

Convert a Python integer pylong to a C void pointer. If pylong cannot be converted, an OverflowError will be raised. This is only assured to produce a usable void pointer for values created with PyLong_FromVoidPtr().

Retorna NULL en caso de error. Use PyErr_Occurred() para desambiguar.

Py_ssize_t PyLong_AsNativeBytes(PyObject *pylong, void *buffer, Py_ssize_t n_bytes, int flags)

Copy the Python integer value pylong to a native buffer of size n_bytes. The flags can be set to -1 to behave similarly to a C cast, or to values documented below to control the behavior.

Returns -1 with an exception raised on error. This may happen if pylong cannot be interpreted as an integer, or if pylong was negative and the Py_ASNATIVEBYTES_REJECT_NEGATIVE flag was set.

Otherwise, returns the number of bytes required to store the value. If this is equal to or less than n_bytes, the entire value was copied. All n_bytes of the buffer are written: large buffers are padded with zeroes.

If the returned value is greater than than n_bytes, the value was truncated: as many of the lowest bits of the value as could fit are written, and the higher bits are ignored. This matches the typical behavior of a C-style downcast.

Nota

Overflow is not considered an error. If the returned value is larger than n_bytes, most significant bits were discarded.

0 will never be returned.

Values are always copied as two’s-complement.

Usage example:

int32_t value;
Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, &value, sizeof(value), -1);
if (bytes < 0) {
    // Failed. A Python exception was set with the reason.
    return NULL;
}
else if (bytes <= (Py_ssize_t)sizeof(value)) {
    // Success!
}
else {
    // Overflow occurred, but 'value' contains the truncated
    // lowest bits of pylong.
}

Passing zero to n_bytes will return the size of a buffer that would be large enough to hold the value. This may be larger than technically necessary, but not unreasonably so.

Nota

Passing n_bytes=0 to this function is not an accurate way to determine the bit length of a value.

If n_bytes=0, buffer may be NULL.

To get at the entire Python value of an unknown size, the function can be called twice: first to determine the buffer size, then to fill it:

// Ask how much space we need.
Py_ssize_t expected = PyLong_AsNativeBytes(pylong, NULL, 0, -1);
if (expected < 0) {
    // Failed. A Python exception was set with the reason.
    return NULL;
}
assert(expected != 0);  // Impossible per the API definition.
uint8_t *bignum = malloc(expected);
if (!bignum) {
    PyErr_SetString(PyExc_MemoryError, "bignum malloc failed.");
    return NULL;
}
// Safely get the entire value.
Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, bignum, expected, -1);
if (bytes < 0) {  // Exception has been set.
    free(bignum);
    return NULL;
}
else if (bytes > expected) {  // This should not be possible.
    PyErr_SetString(PyExc_RuntimeError,
        "Unexpected bignum truncation after a size check.");
    free(bignum);
    return NULL;
}
// The expected success given the above pre-check.
// ... use bignum ...
free(bignum);

flags is either -1 (Py_ASNATIVEBYTES_DEFAULTS) to select defaults that behave most like a C cast, or a combintation of the other flags in the table below. Note that -1 cannot be combined with other flags.

Currently, -1 corresponds to Py_ASNATIVEBYTES_NATIVE_ENDIAN | Py_ASNATIVEBYTES_UNSIGNED_BUFFER.

Flag

Value

Py_ASNATIVEBYTES_DEFAULTS

-1

Py_ASNATIVEBYTES_BIG_ENDIAN

0

Py_ASNATIVEBYTES_LITTLE_ENDIAN

1

Py_ASNATIVEBYTES_NATIVE_ENDIAN

3

Py_ASNATIVEBYTES_UNSIGNED_BUFFER

4

Py_ASNATIVEBYTES_REJECT_NEGATIVE

8

Specifying Py_ASNATIVEBYTES_NATIVE_ENDIAN will override any other endian flags. Passing 2 is reserved.

By default, sufficient buffer will be requested to include a sign bit. For example, when converting 128 with n_bytes=1, the function will return 2 (or more) in order to store a zero sign bit.

If Py_ASNATIVEBYTES_UNSIGNED_BUFFER is specified, a zero sign bit will be omitted from size calculations. This allows, for example, 128 to fit in a single-byte buffer. If the destination buffer is later treated as signed, a positive input value may become negative. Note that the flag does not affect handling of negative values: for those, space for a sign bit is always requested.

Specifying Py_ASNATIVEBYTES_REJECT_NEGATIVE causes an exception to be set if pylong is negative. Without this flag, negative values will be copied provided there is enough space for at least one sign bit, regardless of whether Py_ASNATIVEBYTES_UNSIGNED_BUFFER was specified.

Nota

With the default flags (-1, or UNSIGNED_BUFFER without REJECT_NEGATIVE), multiple Python integers can map to a single value without overflow. For example, both 255 and -1 fit a single-byte buffer and set all its bits. This matches typical C cast behavior.

Added in version 3.13.

int PyUnstable_Long_IsCompact(const PyLongObject *op)
This is Unstable API. It may change without warning in minor releases.

Return 1 if op is compact, 0 otherwise.

This function makes it possible for performance-critical code to implement a “fast path” for small integers. For compact values use PyUnstable_Long_CompactValue(); for others fall back to a PyLong_As* function or PyLong_AsNativeBytes().

The speedup is expected to be negligible for most users.

Exactly what values are considered compact is an implementation detail and is subject to change.

Py_ssize_t PyUnstable_Long_CompactValue(const PyLongObject *op)
This is Unstable API. It may change without warning in minor releases.

If op is compact, as determined by PyUnstable_Long_IsCompact(), return its value.

Otherwise, the return value is undefined.