classes in c++ 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;

Example 3: c++ classes

class SampleClass
{
    int a;
public:
    SampleClass(int v)
    {
        a=v;
    }
    int RetVal()
    {
        return a;
    }
};