_ungetc_nolock, _ungetwc_nolock

Pushes a character back onto the stream.


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


Character to be pushed.

Pointer to FILE structure.

Return value

If successful, each of these functions returns the character argument c. If c can't 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 errno, _doserrno, _sys_errlist, and _sys_nerr.


These functions are non-locking versions of ungetc and ungetwc. The versions with the _nolock suffix are identical except that they aren't protected from interference by other threads. They may be faster since they don't 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 behavior, see Global state in the CRT.

Generic-text routine mappings

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


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

For more compatibility information, see Compatibility.

See also

Stream I/O
getc, getwc
putc, putwc