Create a class named Date with four data members ( year, month, day, day_of_week). Write a program with member functions: one that initializes necessary data members and another that displays today's date in standard format.

 To create a class named Date with four data members (year, month, day, day_of_week) and member functions to initialize data members and display today's date in standard format, we can follow these steps:

1. Define a class named Date with the four data members - year, month, day, and day_of_week.
2. Define a constructor function that initializes the year, month, day, and day_of_week data members to the current date.
3. Define a member function named displayDate() that displays the current date in standard format - "YYYY/MM/DD (Day of Week)".

Here's the C++ code for the above program:

#include <iostream>
#include <ctime>
using namespace std;
class Date {
    private:
        int year, month, day, day_of_week;
    public:
        Date() {
            // Get current date and time
            time_t now = time(0);
            tm *ltm = localtime(&now);
            // Initialize year, month, day, and day_of_week data members
            year = 1900 + ltm->tm_year;
            month = 1 + ltm->tm_mon;
            day = ltm->tm_mday;
            day_of_week = ltm->tm_wday;
        }
        void displayDate() {
            cout << year << "/" << month << "/" << day << " (";
            switch(day_of_week) {
                case 0:
                    cout << "Sunday";
                    break;
                case 1:
                    cout << "Monday";
                    break;
                case 2:
                    cout << "Tuesday";
                    break;
                case 3:
                    cout << "Wednesday";
                    break;
                case 4:
                    cout << "Thursday";
                    break;
                case 5:
                    cout << "Friday";
                    break;
                case 6:
                    cout << "Saturday";
                    break;
            }
            cout << ")" << endl;
        }
};
int main() {
    Date d;
    d.displayDate();
    return 0;
}

Explanation:

• We define a class named Date with the four data members - year, month, day, and day_of_week.
• We define a constructor function that initializes the year, month, day, and day_of_week data members to the current date. We use the C++ time function to get the current date and time, and then extract the year, month, day, and day_of_week data members from the returned tm struct.
• We define a member function named displayDate() that displays the current date in standard format - "YYYY/MM/DD (Day of Week)". We use the C++ cout function to output the year, month, day, and day_of_week data members, and then use a switch statement to output the corresponding day of the week string.
• In the main function, we create an instance of the Date class and call its displayDate() member function to display the current date in standard format.