ungetc(3)                                                     ungetc(3)

  ungetc()

  NAME

    ungetc() - un-get character from input stream

  SYNOPSIS

    #include 

    int ungetc (int c, FILE *stream)

  DESCRIPTION

    The ungetc(3) 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.

    If the value of the argument c character equals EOF, the operation will
    fail and the stream will remain unchanged.

  RETURN VALUES

    The ungetc(3) function returns the character pushed-back after the
    conversion, or EOF if the operation fails.

  SEE ALSO

    getc(3)

    fseek(3)

    setvbuf(3)

  USAGE NOTES

    The ungetc function is thread safe.

    The ungetc function is not async-signal safe.