Should the ARG_TYPE for a CArray be const & or not

Question

What's the difference between these 2 lines

CArray<MyClass, MyClass> MyArray

CArray<MyClass, const MyClass & > MyArray  

Answer 1

The MyClass is always copied to the array. But the first form copies it twice: the first time when its given as a parameter to the Add or SetAt function, the second time internally. With the second form you avoid the first copy.

Answer 2

In the first case you need to have accessable copy constructor in MyClass, and MyClass will be passed by value (copied) in some members of CArray( in CArray::Add for instance).