#include <iostream>;
    using namespace std;

    class Date {
    private:

    public:
        int day;
        int month;
        int year;
        Date();
        Date(int day, int month, int year);
        void Print(Date date);
        Date operator=(const string str);

    };

this is the class cpp file:
#include "Date.h"
Date::Date() {};
Date::Date(int day, int month, int year) :
        day(day),month(month), year(year){};
void Date::Print(Date date) {
    cout << date.day << "/" << date.month << "/" << date.year;
}
Date Date::operator=(string str) {
    Date date;
    date.day = 0; date.month = 0; date.year = 0;
    int i = 0;
    while(str[i] != '/'){
        date.day = (10 * date.day) + (int)str[i++]- 48;
    }
    i++;
    while(str[i] != '/'){
        date.month = (10 * date.month) + (int)str[i++]- 48;
    }
    i++;
    while(i < str.size()){
        date.year = (10 * date.year) + (int)str[i]- 48;
        i++;
    }
    cout << date.day << '/' << date.month << '/' << date.year<< endl;
    return date;
}

#include <iostream>
#include "Date.h"
using namespace std;
int main() {

    Date d,d2(15,7,18);
    string str = "15/7/18";
    d = str;
    cout << d.day<< endl;
    d.Print(d);
    return 0;
}