Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

UNGETC(3)                  Library Functions Manual                  UNGETC(3)

NAME
     ungetc - un-get character from input stream

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdio.h>

     int
     ungetc(int c, FILE *stream);

DESCRIPTION
     The ungetc() function pushes the character c (converted to an unsigned
     char) back onto the input stream pointed to by stream.  The pushed-backed
     characters will be returned by subsequent reads on the stream (in reverse
     order).  A successful intervening call, using the same stream, to one of
     the file positioning functions (fseek(3), fsetpos(3), or rewind(3)) will
     discard the pushed back characters.

     One character of push-back is guaranteed, but as long as there is
     sufficient memory, an effectively infinite amount of pushback is allowed.

     If a character is successfully pushed-back, the end-of-file indicator for
     the stream is cleared.

RETURN VALUES
     The ungetc() function returns the character pushed-back after the
     conversion, or EOF if the operation fails.  If the value of the argument
     c character equals EOF, the operation will fail and the stream will
     remain unchanged.

SEE ALSO
     fseek(3), getc(3), setvbuf(3)

STANDARDS
     The ungetc() function conforms to ANSI X3.159-1989 ("ANSI C89") and IEEE
     Std 1003.1-2001 ("POSIX.1").

HISTORY
     An ungetc() function appeared in Version 7 AT&T UNIX.

NetBSD 10.99                    April 30, 2010                    NetBSD 10.99