This below code will work for c++11 .

using namespace std;

string strings_xor(string s, string t) {

string res = "";
for(int i = 0; i < s.size(); i++) {
    if(s[i] == t[i])
        res = res+'0';
    else
        res = res+'1';
}

return res;

}

int main() { string s, t; cin >> s >> t; cout << strings_xor(s, t) << endl; return 0; }