Go4Expert - can't overload << as member function

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can't overload << as member function

any idea why I can't overload << as member function
i.e

Code:

template<typename T>

class Simple{

    T  A,B;

public:

/* Constructors and destructors  */

    T  getA(){return A;}

     T  getB(){return B;}



   ostream& operator(ostream& os){ return  os<<A<<"-"<<B; } 

   // this doesn't work



}





template<typename T>

ostream& operator(ostream& os, Simple<T> P )

{ return  os<<P.getA()<<"-"<<p.getB(); } 

//this works

I can overload the +, - inside and outside the class.

But << and most probably >> has to be implemented as esternal function , why so ? any idea :)

Re: can't overload << as member function

sorry for the typo . it should read in both operator lines:
"ostream& operator<<(ostream& os, Simple<T> P )"

Re: can't overload << as member function

Because they are not the internal members of the class. the format in which you specify is such that the function needs to be external.

cout<<YourVariable<<endl;

Now if you get into the operator overloading this should be

OutputClassFunction.Operator <<(YourVariable)

And so you need the first parameter as IO class variable and so you cannot have the function as internal.