OOP BasicIs the class declaration right?[const]

Q:
in C++ programming language, Is it right to define a class as the following shown:
class A{
const int Size=0;
}

A:
no, it's wrong!
在C++中，这样是错误的，常量成员的初始化必须在构造函数中完成。
the initiation of const must be intialized in construct function. so the right codes should be following:
    class A
            {
               public  A()
                {
                const int Size=0;
                }
            }

comments:
However, it's not true with C#. with C#, we should exactly code like this:
但是，在C#中，这样是正确的，常量必须在声明的时候同时初始化。因为其在compile-time时候分配heap memory.
class A{
const int Size=0;
}
相反，像C++那种写法还是错误的！所以一定要分清楚
Do not be confused!!!!