void explain_ungetc_or_die(int c, FILE *fp);
int explain_ungetc_on_error(int c, FILE *fp);
DESCRIPTION
The explain_ungetc_or_die function is used to call the
ungetc(3) system call. On failure an explanation will be printed to
stderr, obtained from the explain_ungetc(3) function, and
then the process terminates by calling exit(EXIT_FAILURE).
The explain_ungetc_on_error function is used to call the
ungetc(3) system call. On failure an explanation will be printed to
stderr, obtained from the explain_ungetc(3) function, but
still returns to the caller.
c
The c, exactly as to be passed to the ungetc(3) system call.
fp
The fp, exactly as to be passed to the ungetc(3) system call.
RETURN VALUE
The explain_ungetc_or_die function only returns on success, see
ungetc(3) for more information. On failure, prints an explanation
and exits, it does not return.
The explain_ungetc_on_error function always returns the value
return by the wrapped ungetc(3) system call.
EXAMPLE
The explain_ungetc_or_die function is intended to be used in a
fashion similar to the following example: