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.


// 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)

// Returns host information corresponding to host name
void checkHostEntry(struct hostent * hostentry)
    if (hostentry == NULL)

// Converts space-delimited IPv4 addresses
// to dotted-decimal format
void checkIPbuffer(char *IPbuffer)
    if (NULL == IPbuffer)

// Driver code
int main()
    char hostbuffer[256];
    char *IPbuffer;
    struct hostent *host_entry;
    int hostname;

    // To retrieve hostname
    hostname = gethostname(hostbuffer, sizeof(hostbuffer));

    // To retrieve host information
    host_entry = gethostbyname(hostbuffer);

    // To convert an Internet network
    // address into ASCII string
    IPbuffer = inet_ntoa(*((struct in_addr*)

    printf("Hostname: %s\n", hostbuffer);
    printf("Host IP: %s", IPbuffer);

    return 0;


Hostname: cContainer
Host IP:

Output varies machine to machine

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