Question

data member inside a class can be const but only if its static.
otherwise we need to have a constructor to initialize a constant inside a class.

can we declare a const data member inside a class? //this was an interview question

It seems to me that we can, but is it appropriate for a programmer to declare a constant inside a class.

please give some explanation/reasons, why we can or cannot do?

Answer 1

Off course you can :

struct A
{
    A() : a(5)
    {
    }
    const int a;
};

int main()
{
   A a;
}

This means that the data member a, inside struct A is not going to change.