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@(#)ungetc.3 8.1 (Berkeley) 6/4/93
$FreeBSD$
.Dd June 4, 1993 .Dt UNGETC 3 .Os .Sh NAME .Nm ungetc .Nd un-get character from input stream .Sh LIBRARY .Lb libc .Sh SYNOPSIS n stdio.h .Ft int .Fn ungetc "int c" "FILE *stream" .Sh DESCRIPTION The .Fn ungetc function pushes the character .Fa c (converted to an unsigned char) back onto the input stream pointed to by .Fa stream . The pushed-back 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 .Xr ( fseek 3 , .Xr fsetpos 3 , or .Xr rewind 3 ) will discard the pushed back characters.
p One character of push-back is guaranteed, but as long as there is sufficient memory, an effectively infinite amount of pushback is allowed.
p If a character is successfully pushed-back, the end-of-file indicator for the stream is cleared. The file-position indicator is decremented by each successful call to .Fn ungetc ; if its value was 0 before a call, its value is unspecified after the call. .Sh RETURN VALUES The .Fn ungetc function returns the character pushed-back after the conversion, or .Dv EOF if the operation fails. If the value of the argument .Fa c character equals .Dv EOF , the operation will fail and the stream will remain unchanged. .Sh SEE ALSO .Xr fseek 3 , .Xr getc 3 , .Xr setvbuf 3 , .Xr ungetwc 3 .Sh STANDARDS The .Fn ungetc function conforms to .St -isoC .