C Programming Code Examples

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C Program to Display the IP Address of the System

C Program to Display the IP Address of the System

- Create a socket to define network interface IPv4.
- Define the IPv4 address type.
- Define the port name where network is attached.
- Access the network interface information by passing address using ioctl.
- Extract the IP address.

    #include <stdio.h>

    #include <string.h>

    #include <sys/types.h>

    #include <sys/socket.h>

    #include <sys/ioctl.h>

    #include <netinet/in.h>

    #include <net/if.h>

    #include <unistd.h>

    #include <arpa/inet.h>

    int main()

    {

        int n;

        struct ifreq ifr;

        char array[] = "xw23";

        n = socket(AF_INET, SOCK_DGRAM, 0);

        //Type of address to retrieve - IPv4 IP address

        ifr.ifr_addr.sa_family = AF_INET;

        //Copy the interface name in the ifreq structure

        strncpy(ifr.ifr_name , array , IFNAMSIZ - 1);

        ioctl(n, SIOCGIFADDR, &ifr);

        close(n);

        //display result

        printf("IP Address is %s - %s\n" , array , inet_ntoa(( (struct sockaddr_in *)&ifr.ifr_addr )->sin_addr) );

        return 0;

    }

- Create a socket to define network interface IPv4 using statement socket(AF_INET, SOCK_DGRAM, 0) and store it in the variable n.
- Define the IPv4 address type by assigning AF_INET to (ifr.ifr_addr.sa_family).
- Define the port name where network is attached using statement strncpy(ifr.ifr_name , array , IFNAMSIZ - 1), where array is initialized with string "xw23".
- Call the ioctl function to access the network interface information by passing the address.
- Close the variable n.
- Use this (inet_ntoa(( (struct sockaddr_in *)&ifr.ifr_addr )->sin_addr)) to extract the IP address and print the same as output.