bsd man page for ungetc

UNGETC(3S)																UNGETC(3S)

NAME
       ungetc - push character back into input stream

SYNOPSIS
       #include <stdio.h>

       ungetc(c, stream)
       FILE *stream;

DESCRIPTION
       Ungetc  pushes  the  character  c  back	on an input stream.  That character will be returned by the next getc call on that stream.  Ungetc
       returns c.

       One character of pushback is guaranteed provided something has been read from the stream and the stream is actually buffered.  Attempts	to
       push EOF are rejected.

       Fseek(3S) erases all memory of pushed back characters.

SEE ALSO
       getc(3S), setbuf(3S), fseek(3S)

DIAGNOSTICS
       Ungetc returns EOF if it can't push a character back.

7th Edition							   May 15, 1985 							UNGETC(3S)