34.2. msvcrt — 来自 MS VC++ 运行时的有用例程


这些函数提供了对 Windows 平台上一些有用功能的访问。一些更高级别的模块使用这些函数来构建其服务的 Windows 实现。 例如, getpass 模块在实现 getpass() 函数时使用了这些函数。

关于这些函数的更多信息可以在平台 API 文档中找到。

该模块实现了控制台 I/O API 的普通和宽字符变体。普通的 API 只处理ASCII字符,国际化应用受限。应该尽可能地使用宽字符 API 。

在 3.3 版更改: Operations in this module now raise OSError where IOError was raised.

34.2.1. File Operations

msvcrt.locking(fd, mode, nbytes)

Lock part of a file based on file descriptor fd from the C runtime. Raises OSError on failure. The locked region of the file extends from the current file position for nbytes bytes, and may continue beyond the end of the file. mode must be one of the LK_* constants listed below. Multiple regions in a file may be locked at the same time, but may not overlap. Adjacent regions are not merged; they must be unlocked individually.

msvcrt.LK_LOCK
msvcrt.LK_RLCK

Locks the specified bytes. If the bytes cannot be locked, the program immediately tries again after 1 second. If, after 10 attempts, the bytes cannot be locked, OSError is raised.

msvcrt.LK_NBLCK
msvcrt.LK_NBRLCK

Locks the specified bytes. If the bytes cannot be locked, OSError is raised.

msvcrt.LK_UNLCK

Unlocks the specified bytes, which must have been previously locked.

msvcrt.setmode(fd, flags)

Set the line-end translation mode for the file descriptor fd. To set it to text mode, flags should be os.O_TEXT; for binary, it should be os.O_BINARY.

msvcrt.open_osfhandle(handle, flags)

Create a C runtime file descriptor from the file handle handle. The flags parameter should be a bitwise OR of os.O_APPEND, os.O_RDONLY, and os.O_TEXT. The returned file descriptor may be used as a parameter to os.fdopen() to create a file object.

msvcrt.get_osfhandle(fd)

Return the file handle for the file descriptor fd. Raises OSError if fd is not recognized.

34.2.2. Console I/O

msvcrt.kbhit()

Return true if a keypress is waiting to be read.

msvcrt.getch()

Read a keypress and return the resulting character as a byte string. Nothing is echoed to the console. This call will block if a keypress is not already available, but will not wait for Enter to be pressed. If the pressed key was a special function key, this will return '\000' or '\xe0'; the next call will return the keycode. The Control-C keypress cannot be read with this function.

msvcrt.getwch()

Wide char variant of getch(), returning a Unicode value.

msvcrt.getche()

Similar to getch(), but the keypress will be echoed if it represents a printable character.

msvcrt.getwche()

Wide char variant of getche(), returning a Unicode value.

msvcrt.putch(char)

Print the byte string char to the console without buffering.

msvcrt.putwch(unicode_char)

Wide char variant of putch(), accepting a Unicode value.

msvcrt.ungetch(char)

Cause the byte string char to be “pushed back” into the console buffer; it will be the next character read by getch() or getche().

msvcrt.ungetwch(unicode_char)

Wide char variant of ungetch(), accepting a Unicode value.

34.2.3. Other Functions

msvcrt.heapmin()

Force the malloc() heap to clean itself up and return unused blocks to the operating system. On failure, this raises OSError.