ungetc(3) - NetBSD Manual Pages

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UNGETC(3)               NetBSD 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 suffi-
     cient 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 conver-
     sion, 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 7.0                      April 30, 2010                      NetBSD 7.0