35.2. msvcrt – Useful routines from the MS VC++ runtime
Platforms: Windows
These functions provide access to some useful capabilities on Windows platforms.
Some higher-level modules use these functions to build the Windows
implementations of their services. For example, the getpass module uses
this in the implementation of the getpass() function.
Further documentation on these functions can be found in the Platform API
documentation.
The module implements both the normal and wide char variants of the console I/O
api. The normal API deals only with ASCII characters and is of limited use
for internationalized applications. The wide char API should be used where
ever possible
35.2.1. File Operations
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msvcrt.locking(fd, mode, nbytes)
- Lock part of a file based on file descriptor fd from the C runtime. Raises
IOError 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.
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msvcrt.LK_LOCK
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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, IOError is raised.
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msvcrt.LK_NBLCK
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msvcrt.LK_NBRLCK
- Locks the specified bytes. If the bytes cannot be locked, IOError is
raised.
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msvcrt.LK_UNLCK
- Unlocks the specified bytes, which must have been previously locked.
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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.
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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.
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msvcrt.get_osfhandle(fd)
- Return the file handle for the file descriptor fd. Raises IOError if
fd is not recognized.
35.2.2. Console I/O
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msvcrt.kbhit()
- Return true if a keypress is waiting to be read.
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msvcrt.getch()
- Read a keypress and return the resulting character. 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.
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msvcrt.getwch()
Wide char variant of getch(), returning a Unicode value.
New in version 2.6.
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msvcrt.getche()
- Similar to getch(), but the keypress will be echoed if it represents a
printable character.
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msvcrt.getwche()
Wide char variant of getche(), returning a Unicode value.
New in version 2.6.
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msvcrt.putch(char)
- Print the character char to the console without buffering.
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msvcrt.putwch(unicode_char)
Wide char variant of putch(), accepting a Unicode value.
New in version 2.6.
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msvcrt.ungetch(char)
- Cause the character char to be “pushed back” into the console buffer; it will
be the next character read by getch() or getche().
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msvcrt.ungetwch(unicode_char)
Wide char variant of ungetch(), accepting a Unicode value.
New in version 2.6.
35.2.3. Other Functions
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msvcrt.heapmin()
- Force the malloc heap to clean itself up and return unused blocks to
the operating system. This only works on Windows NT. On failure, this raises
IOError.
