ungetc(3) [netbsd man page]

UNGETC(3)						   BSD 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.

BSD
								  April 30, 2010							       BSD

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)