C++ Program to implements Constructor

Here, we are initializing the parameter of rectangle to calculate area using constructor.

// class constructor
 #include <iostream>
 using namespace std;
 class Rectangle
 {
 int width, height;
 public:
 Rectangle (int, int);
 int area ()
   {
     return (width * height);
   }
 };
 Rectangle::Rectangle (int a, int b)
 {
 width = a;
 height = b;
 } 
 int
 main ()
 {
 Rectangle rect (3, 4);
 Rectangle rectb (5, 6);
 cout << "rect area: " << rect.area () << endl;
 cout << "rectb area: " << rectb.area () << endl;
 return 0;
 }

Output

rect area: 12 
rectb area: 30