how to use class in c++ code example

Example 1: how to write a class in c++

class Rectangle 
{
	int width, height;
public:
	void set_values (int,int);
    int area() {return width*height;}
};

void Rectangle::set_values (int x, int y)
{
	width = x;
	height = y;
}

Example 2: classes c++

class Rectangle {
    int width, height;
  public:
    void set_values (int,int);
    int area (void);
} rect;