Custom C ++ class method call

As demand rectangle, circle area method, area can be written as a class

area.h only declared, not to achieve:

AREA_H #ifndef // prevent duplicate references 
#define AREA_H
 class Area { // custom class 
public :
     Double RectArea ( Double length, Double width); // class declaration function 
    Double CircleArea ( Double R & lt); 
}; 
#endif

area.cpp implemented:

#include "stdafx.h"
#include"area.h"//引入头文件

double area::RectArea(double x, double y)//具体实现
{
    return x*y;
}
double area::CircleArea(double r) {
    return(2 * 3.14*r);
}

transfer:

#include " the stdafx.h " 
#include <the iostream> 
#include " area.h " // introducing 

the using  namespace STD; 

int main () 
{ 
    Area S; // Create Object 
    Double Result = s.RectArea ( 2 , . 3 ); // Object method 
    COUT Result << << endl;
     return  0 ; 
}