|UNGETC(3)||Library Functions Manual||UNGETC(3)|
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.
ungetc() function returns the character pushed-back after the conversion, or
EOFif the operation fails. If the value of the argument c character equals
EOF, the operation will fail and the stream will remain unchanged.
ungetc() function conforms to ANSI X3.159-1989 (“ANSI C89”).
ungetc() function first appeared in Version 7 AT&T UNIX.
|December 1, 2017||OpenBSD-current|