hello.c

/**
 * @example hello.c
 * This example is an introduction to using the library.
 *
 * Note the different situations in which the two functions are called. errc()
 * is called when the program encounters a state that it doesn't know how to
 * handle. warn() is called when an unusual but managable condition is found.
 */
 
#include <stdio.h>
#include <stdlib.h>
 
#include "../err.h"
 
int
main(int argc, char *argv[])
{
        char *word;
 
        program_invocation_name = argv[0];
 
        if (argc > 2)
                errc(argc, "multiple arguments provided");
        else if (argc == 1) {
                warn("no argument provided, using default word\n");
                word = "world";
        } else
                word = argv[1];
 
        printf("Hello, %s!\n", word);
 
        return EXIT_SUCCESS;
}