How to Get Client IP Address in C

#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>

int main()
    int fd;
    struct ifreq ifr;

    fd = socket(AF_INET, SOCK_DGRAM, 0);

    ifr.ifr_addr.sa_family = AF_INET;

    snprintf(ifr.ifr_name, IFNAMSIZ, "eth0");

    ioctl(fd, SIOCGIFADDR, &ifr);

    /* and more importantly */
    printf("%s\n", inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr));

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.