Setting IP address in Linux using c++ - c++

Question

I want to set my IP, subnet, DHCP addresses but I need to do it by using c++. I have researched on the internet and tried some code. Unfortunately, it didn't work. And one more thing it supposes to be secure to run it, I mean I cannot use functions that need privilege like system() and so on. Is there any advice you can give me?
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>
int main()
{
char ip_address[15];
int fd;
struct ifreq ifr;
struct sockaddr_in *addr;
/*Read IP Address*/
printf("Enter Ip Address: ");
scanf("%s",ip_address);
/*AF_INET - to define network interface IPv4*/
/*Creating soket for it.*/
fd = socket(AF_INET, SOCK_DGRAM, 0);
/*AF_INET - to define IPv4 Address type.*/
ifr.ifr_addr.sa_family = AF_INET;
/*eth0 - define the ifr_name - port name
where network attached.*/
memcpy(ifr.ifr_name, "eth0", IFNAMSIZ-1);
/*defining the sockaddr_in*/
addr=(struct sockaddr_in *)&ifr.ifr_addr;
/*convert ip address in correct format to write*/
inet_pton(AF_INET,ip_address,&addr->sin_addr);
/*Setting the Ip Address using ioctl*/
ioctl(fd, SIOCSIFADDR, &ifr);
/*closing fd*/
close(fd);
printf("IP Address updated sucessfully.\n");
/*Getting the Ip Address after Updating.*/
/*clear ip_address buffer with 0x20- space*/
memset((unsigned char*)ip_address,0x20,15);
ioctl(fd, SIOCGIFADDR, &ifr);
/*Extracting Ip Address*/
strcpy(ip_address,inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr));
printf("Updated IP Address is: %s\n",ip_address);
return 0;
}
This code is what I have tried so far. After I run this I check ifconfig but nothing is changed.