An exercise am working on, I created two classes, Book & Date. The Date constructor simply takes 3 int arguments for day, month and year. The Book constructor takes string isbn, string title, string author, Date copyright_date.

I thought i could use the Date constructor to create a Date object inside the Book constructor but it doesnt seem to be working.

#include <bits/stdc++.h>
using namespace std;
class Date{
public:
    class Invalid{};//to throw in error
    Date(int d,int m,int y);
    Date() = default;

    //getters
    int get_day(){return day;};
    int get_month(){return month;};
    int get_year(){return year;};

    //helper functions

private:
    int day{1};
    int month{1};
    int year{2024};
    bool is_valid();

};
Date::Date(int d,int m,int y):day{d},month{m},year{y}
{
    if(!is_valid()) throw Date::Invalid{};
}

bool Date::is_valid(){
    return(month<1||12<month)? false: true;
}

ostream& operator << (ostream& os, Date d){ //operator overload to display Date objects
    return os<<d.get_day()<<'-'<<d.get_month()<<'-'<<d.get_year()<<endl;
}

class Book{
public:
    //constructors
    Book():ISBN("xxx-xx-x"),title("title"),author("Aloy"),copyright_date(Date() )   {}//default constructor
    Book(string isbn,string t,string a,Date c):ISBN(isbn),title(t),author(a),copyright_date(c)   {}

    //getters
    string get_ISBN(){ return ISBN; }
    string get_title(){ return title; }
    string get_author(){ return author; }
    Date get_copyright_date(){ return copyright_date; }
    void print_info(){ cout<<"Book title: "<<title<<"nAuthor: "<<author<<"nISBN: "<<ISBN<<"nCopyright date: "<<copyright_date<<"Status: "<< ((is_checked_out)? "Checked out":"Available")<<endl; }

    //setters
    void set_ISBN(string i){ ISBN=i; }
    void set_title(string t){ title=t; }
    void set_author(string a){ author=a; }
    void set_copyright_date(Date d){ copyright_date=d; }

    void check_in(){ is_checked_out = false; }
    void check_out(){ is_checked_out = true; }
    void check(){ (is_checked_out)? cout<<"Out"<<endl : cout<<"Available"<<endl; }

private:
    string ISBN;
    string title;
    string author;
    Date copyright_date;
    bool is_checked_out{false};
};

bool operator==(Book& b1, Book& b2){
    return b1.get_ISBN()==b2.get_ISBN();
}

 int main()
{
    Book book1{"233-725-C2","Shadow of Mordor","J.R.R.Tolkien",Date dd(14,7,1954)};

    book1.print_info();
     return 0;
 }