_ungetc_nolock, _ungetwc_nolock

Pushes a character back onto the stream without locking.

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 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.

Remarks

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

Requirements

For more compatibility information, see Compatibility.

See also

Stream I/O
getc, getwc
putc, putwc