C Program to display hostname and IP address

In this section we will see how to see the Host name and IP address of the local system in an easier way. We will write a C program to find the host name and IP.

Some of the following functions are used. These functions have different task. Let us see the functions and their tasks.

Example Code

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <netdb.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> void check_host_name(int hostname) { //This function returns host name for    local computer    if (hostname == -1) {       perror("gethostname");       exit(1);    } } void check_host_entry(struct hostent * hostentry) { //find host info from    host name    if (hostentry == NULL) {       perror("gethostbyname");       exit(1);    } } void IP_formatter(char *IPbuffer) { //convert IP string to dotted decimal    format    if (NULL == IPbuffer) {       perror("inet_ntoa");       exit(1);    } } main() {    char host[256];    char *IP;    struct hostent *host_entry;    int hostname;   hostname = gethostname(host, sizeof(host)); //find the host name check_host_name(hostname); host_entry = gethostbyname(host); //find host information check_host_entry(host_entry); IP = inet_ntoa(*((struct in_addr*) host_entry->h_addr_list[0])); //Convert into IP string printf("Current Host Name: %s
", host); printf("Host IP: %s
", IP); }

Output (Tested on Linux System)

Current Host Name: soumyadeep-VirtualBox Host IP: 127.0.1.1