A simple "die" function for C - example of variable number of arguments

This page was created on Sun Jul 11 2010 and last changed on Sat Oct 05 2024.

This simple function illustrates receiving and sending out a variable number of arguments in C using <stdarg.h>.

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>

static void die (int line_number, const char * format, ...)
{
    va_list vargs;
    va_start (vargs, format);
    fprintf (stderr, "%d: ", line_number);
    vfprintf (stderr, format, vargs);
    fprintf (stderr, ".\n");
    va_end (vargs);
    exit (1);
}

int main (int argc, char ** argv)
{
    if (argc == 1) {
	die (__LINE__, "%s: I need more arguments", argv[0]);
    }
    return 0;
}

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The output of this program looks like this:

19: ./die: I need more arguments.

Here is the makefile to compile and run this and print the example:

die.txt: die
        -./die > $@ 2>&1

die: die.c
        cc -Wall -g -o $@ die.c

clean:
        rm -f die die.txt

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