Sum of two integers without using +/- operators

/* Problem Description: Sum of two integers without using +/- operators.
 * Author: HTA
 * Date: July 13, 2016
 */

#include <iostream>
using namespace std;

int add(int,int);

int main(void) {
    int a,b;
    cout << "Give a: "; cin >> a;
    cout << endl << "Give b: "; cin >> b;
    cout << endl << "The Sum is: " << add(a,b) << endl;
    return 0;
}

int add(int x, int y) {
    if (y==0)
        return x;
    else {
        int sum= x^y;
        int carry= (x&y)<< 1;
        add(sum,carry);
    }
}

// alternative:
/*
 *#include <iostream>
 *using namespace std;
 *
 *int main(void) {
 *   int a,b;
 *   cout << "Give a: "; cin >> a;
 *   cout << endl << "Give b: "; cin >> b;
 *   int sum,carry;
 *   while (b!=0) {
 *       sum= a^b;
 *       carry= (a&b);
 *       a=sum;
 *       b=carry <<1;
 *   }
 *   cout << endl << "The Sum is: " << a << endl;
 *   return 0;
 *}
 */