opensolaris man page for ungetc

ungetc(3C)						   Standard C Library Functions 						ungetc(3C)

NAME
       ungetc - push byte back into input stream

SYNOPSIS
       #include <stdio.h>

       int ungetc(int c, FILE *stream);

DESCRIPTION
       The  ungetc()  function pushes the byte specified by c (converted to an unsigned char) back onto the input stream pointed to by stream. The
       pushed-back bytes will be returned by subsequent reads on that stream in the reverse order of their pushing. A successful intervening  call
       (with  the  stream  pointed  to	by stream) to a file-positioning function ( fseek(3C), fsetpos(3C) or rewind(3C)) discards any pushed-back
       bytes for the stream. The external storage corresponding to the stream is unchanged.

       Four bytes of push-back are guaranteed.	If ungetc() is called too many times on the same stream without an intervening read or	file-posi-
       tioning operation on that stream, the operation may fail.

       If the value of c equals that of the macro EOF, the operation fails and the input stream is unchanged.

       A  successful  call  to	ungetc()  clears the end-of-file indicator for the stream. The value of the file-position indicator for the stream
       after reading or discarding all pushed-back bytes will be the same as it was before the bytes were pushed back. The file-position indicator
       is decremented by each successful call to ungetc(); if its value was 0 before a call, its value is indeterminate after the call.

RETURN VALUES
       Upon successful completion, ungetc() returns the byte pushed back after conversion.  Otherwise it returns EOF.

ERRORS
       No errors are defined.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       read(2), Intro(3), __fsetlocking(3C), fseek(3C), fsetpos(3C), getc(3C), setbuf(3C), stdio(3C), attributes(5), standards(5)

SunOS 5.11							    10 Sep 2003 							ungetc(3C)