gethostbyname.c

#include <stdio.h> 
#include <stdlib.h> 
#include <errno.h> 
#include <netdb.h> 
#include <sys/types.h>
#include <netinet/in.h> 
#include <sys/socket.h>
#include <arpa/inet.h>

int main(int argc, char *argv[])
{
    struct hostent *h;

    if (argc != 2) {  /* error check the command line */
	fprintf(stderr,"usage: getip address\n");
	exit(1);
    }

    if ((h=gethostbyname(argv[1])) == NULL) {  /* get the host info */
	herror("gethostbyname");
	exit(1);
    }

    printf("Host name  : %s\n", h->h_name);
    printf("IP Address : %s\n",inet_ntoa(*((struct in_addr *)h->h_addr)));

    return 0;
}