Ответ:

#include <iostream>

#include <string>

using namespace std;

class Human {

public:

   Human (string name, int day, int month, int year) : name_(move(name)), day_(day), month_(month), year_(year) {}

   int age() {

       int days = time(0) / (24 * 3600) + 365 * 1970;

       return (days - day_ - month_ * 30 - year_* 365) / 365;

   }

private:

   string name_;

   int day_;

   int month_;

   int year_;

};

int main () {

   Human lol("S", 1, 1, 2000);

   cout << lol.age();

}