UNGETC(3)

NAME
ungetc - un-get character from input stream

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 ansiC.

HISTORY
The ungetc() function first appeared in AT&T UNIX.