_ungetc_nolock, _ungetwc_nolock

Artiklu
08/03/2021
2 minuti biex taqra

Pushes a character back onto the stream.

Syntax

int _ungetc_nolock(
   int c,
   FILE *stream
);
wint_t _ungetwc_nolock(
   wint_t c,
   FILE *stream
);

Parameters

c
Character to be pushed.

stream
Pointer to FILE structure.

Return Value

If successful, each of these functions returns the character argument c. If c cannot be pushed back or if no character has been read, the input stream is unchanged and _ungetc_nolock returns EOF; _ungetwc_nolock returns WEOF. If stream is NULL, EOF or WEOF is returned and errno is set to EINVAL.

For information on these and other error codes, see _doserrno, errno, _sys_errlist, and _sys_nerr.

Remarks

These functions are non-locking versions of ungetc and ungetwc. The versions with the _nolock suffix are identical except that they are not protected from interference by other threads. They may be faster since they do not incur the overhead of locking out other threads. Use these functions only in thread-safe contexts such as single-threaded applications or where the calling scope already handles thread isolation.

By default, this function's global state is scoped to the application. To change this, see Global state in the CRT.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
_ungettc_nolock	_ungetc_nolock	_ungetc_nolock	_ungetwc_nolock

Requirements

Routine	Required header
_ungetc_nolock	<stdio.h>
_ungetwc_nolock	<stdio.h> or <wchar.h>

For additional compatibility information, see Compatibility.