C Program to display hostname and IP address

There are many ways to find Hostname and IP address of a local machine. Here is a simple method to find hostname and IP address using C program.

We will be using the following functions :-

gethostname() : The gethostname function retrieves the standard host name for the local computer.

gethostbyname() : The gethostbyname function retrieves host information corresponding to a host name from a host database.

inet_ntoa() : The inet_ntoa function converts an (Ipv4) Internet network address into an ASCII string in Internet standard dotted-decimal format.

Code:

C/C++

// C program to display hostname // and IP address #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>    // Returns hostname for the local computer void checkHostName(int hostname) {     if (hostname == -1)     {         perror("gethostname");         exit(1);     } }    // Returns host information corresponding to host name void checkHostEntry(struct hostent * hostentry) {     if (hostentry == NULL)     {         perror("gethostbyname");         exit(1);     } }    // Converts space-delimited IPv4 addresses // to dotted-decimal format void checkIPbuffer(char *IPbuffer) {     if (NULL == IPbuffer)     {         perror("inet_ntoa");         exit(1);     } }    // Driver code int main() {     char hostbuffer[256];     char *IPbuffer;     struct hostent *host_entry;     int hostname;        // To retrieve hostname     hostname = gethostname(hostbuffer, sizeof(hostbuffer));     checkHostName(hostname);        // To retrieve host information     host_entry = gethostbyname(hostbuffer);     checkHostEntry(host_entry);        // To convert an Internet network     // address into ASCII string     IPbuffer = inet_ntoa(*((struct in_addr*)                            host_entry->h_addr_list[0]));        printf("Hostname: %s\n", hostbuffer);     printf("Host IP: %s", IPbuffer);        return 0; }

Output:

Hostname: cContainer
Host IP: 10.98.162.101