ungetc(3) - NetBSD Manual Pages

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UNGETC(3)                 NetBSD Programmer's Manual                 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 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

     getc(3),  fseek(3),  setvbuf(3)


STANDARDS

     The ungetc() function conforms to ANSI X3.159-1989 (``ANSI C'').

4.4BSD                           June 4, 1993                                1