_ungetc_nolock, _ungetwc_nolock

Article
06/05/2017

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The latest version of this topic can be found at _ungetc_nolock, _ungetwc_nolock.

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.

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 in the Introduction.

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

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