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127 lines
3.5 KiB
ReStructuredText
127 lines
3.5 KiB
ReStructuredText
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:mod:`msvcrt` -- Useful routines from the MS VC++ runtime
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=========================================================
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.. module:: msvcrt
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:platform: Windows
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:synopsis: Miscellaneous useful routines from the MS VC++ runtime.
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.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
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These functions provide access to some useful capabilities on Windows platforms.
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Some higher-level modules use these functions to build the Windows
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implementations of their services. For example, the :mod:`getpass` module uses
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this in the implementation of the :func:`getpass` function.
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Further documentation on these functions can be found in the Platform API
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documentation.
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.. _msvcrt-files:
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File Operations
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---------------
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.. function:: locking(fd, mode, nbytes)
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Lock part of a file based on file descriptor *fd* from the C runtime. Raises
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:exc:`IOError` on failure. The locked region of the file extends from the
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current file position for *nbytes* bytes, and may continue beyond the end of the
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file. *mode* must be one of the :const:`LK_\*` constants listed below. Multiple
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regions in a file may be locked at the same time, but may not overlap. Adjacent
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regions are not merged; they must be unlocked individually.
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.. data:: LK_LOCK
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LK_RLCK
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Locks the specified bytes. If the bytes cannot be locked, the program
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immediately tries again after 1 second. If, after 10 attempts, the bytes cannot
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be locked, :exc:`IOError` is raised.
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.. data:: LK_NBLCK
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LK_NBRLCK
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Locks the specified bytes. If the bytes cannot be locked, :exc:`IOError` is
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raised.
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.. data:: LK_UNLCK
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Unlocks the specified bytes, which must have been previously locked.
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.. function:: setmode(fd, flags)
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Set the line-end translation mode for the file descriptor *fd*. To set it to
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text mode, *flags* should be :const:`os.O_TEXT`; for binary, it should be
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:const:`os.O_BINARY`.
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.. function:: open_osfhandle(handle, flags)
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Create a C runtime file descriptor from the file handle *handle*. The *flags*
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parameter should be a bit-wise OR of :const:`os.O_APPEND`, :const:`os.O_RDONLY`,
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and :const:`os.O_TEXT`. The returned file descriptor may be used as a parameter
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to :func:`os.fdopen` to create a file object.
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.. function:: get_osfhandle(fd)
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Return the file handle for the file descriptor *fd*. Raises :exc:`IOError` if
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*fd* is not recognized.
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.. _msvcrt-console:
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Console I/O
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-----------
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.. function:: kbhit()
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Return true if a keypress is waiting to be read.
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.. function:: getch()
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Read a keypress and return the resulting character. Nothing is echoed to the
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console. This call will block if a keypress is not already available, but will
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not wait for :kbd:`Enter` to be pressed. If the pressed key was a special
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function key, this will return ``'\000'`` or ``'\xe0'``; the next call will
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return the keycode. The :kbd:`Control-C` keypress cannot be read with this
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function.
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.. function:: getche()
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Similar to :func:`getch`, but the keypress will be echoed if it represents a
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printable character.
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.. function:: putch(char)
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Print the character *char* to the console without buffering.
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.. function:: ungetch(char)
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Cause the character *char* to be "pushed back" into the console buffer; it will
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be the next character read by :func:`getch` or :func:`getche`.
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.. _msvcrt-other:
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Other Functions
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---------------
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.. function:: heapmin()
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Force the :cfunc:`malloc` heap to clean itself up and return unused blocks to
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the operating system. This only works on Windows NT. On failure, this raises
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:exc:`IOError`.
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