C++ operator _operator casting

Nowadays, focus on the study of the C++ operator, puzzled sometimes. Write here to make sure the clearly understanding.

The demo code from the internet.

First, define a class named CArea, In this class, we declare a operator name "float", in order to tell to compiler this object can transfer to a float type.

e.g. 

CArea a;

float b;

and our code may like this : b = a;  // cool! transfer a CArea object to a float type.

class CArea{       float area;public:       CArea()       {              area=0;       }       CArea(float a)                 {              area=a;       }       void getArea()       {              cout<<area<<endl;       }       void setArea(float a)       {              area=a;       }       operator float()                   {              return area;       }};

and another class named CCircle. In this class, we declare another operator CArea in order to tell the compiler the CCircle object can be transfer to type CArea.

e.g.

CCricle a;

CArea b;

and our code may like this : b = a;  // Transfer a CCircle object to a CArea type. Of course in the function we need to do the real converting

class CCircle{       float R;public:       void getR()       {              cout<<R<<endl;       }       void setR(float r)       {              R=r;       }       operator CArea()         {                                               float area=3.1415926*R*R;              return (CArea(area));       }};

ok, when two base classes are ready, we can do some test work like following:

int main(){       CCircle cir;       CArea are;       float a;       cir.setR(5);       cir.getR();                           are.getArea();                  are=cir;                       are.getArea();              a=are;                               cout<<a<<endl;       char *tt;       cin>>tt;       return 0;}

More, we can define a var to do a direct transformation. and we can change the code as following:

int main(){       CCircle cir;       CArea are;       float a;       cir.setR(5);       cir.getR();       are.getArea();       //are=cir;       CArea aa(cir);       aa.getArea();       //a=are;       float b(aa);       cout<<b<<endl;       char *tt;       cin>>tt;       return 0;}

Finally, I understand how it works. funny!