Question about Class

[shynchan]

I have a problem about Class. See

Class A
{
public:
//copy constructor
A(A& );    //here, I dont know why it is 
A&
 but not 
A
//other ...
}

eh,who can tell me why.
thank u

[PanGalactic]

The value parameter A has to be copied, the reference parameter does not. The value parameter version assumes a copy constructor, which you are making.

In other words, for A(A) to work, A(A) has to already exist. This is because A(A) says "pass me a copy of A".

[Bazzy]

Here is a detailed explanation on arguments passed by reference: http://www.cplusplus.com/doc/tutorial/functions2/