assign

Example by: Ira Oldham, References: Savitch eighth edition, section 10.2; Gaddis seventh edition, section 14.3

If your class only contains primitive data types such as int or double, the assignment operator can be used to copy an object that is a member of this class.

1  class Date
2  {
3    int day;
4    int month;
5    int year;
6    bool validate(int day_parm, int month_parm, int year_parm);
7  public:
8    bool set_date(int day_parm, int month_parm, int year_parm);
9    void print_date();
10   int  get_day()   {return day;}
11   int  get_month() {return month;}
12   int  get_year()  {return year;}
13 };
14 int main(void)
15 {
16   Date today;
...
17     cout << "Date: ";
18     today.print_date();
19     Date date_copy = today;
20     cout << "Date: ";
21     date_copy.print_date();
...
22}
23 void Date::print_date()
24 {
25   cout << month << '/' << day << '/' << year << endl;
26 }

Input date:
day:   31
month: 12
year:  1234
Date: 12/31/1234
Date: 12/31/1234

• line 9 in the class Date declares a print_date member function.
• lines 17-18 are in the main function. They prints the Date today.
• line 19 Initializes the date_copy object with a copy the int values from the today object.
• lines 20-21 print the copy.
• lines 23-26 are the definition of the print_date method.

If each one of the member data in a class has a primitive data type (not pointers or references), the assignment operator can be used to copy an object that is a member of that class.