Is this C++ structure initialization trick safe?

Question

Instead of having to remember to initialize a simple \'C\' structure, I might derive from it and zero it in the constructor like this:

struct MY_STRUCT
{
            


        

Answer 1

This is a perfect example of porting a C idiom to C++ (and why it might not always work...)

The problem you will have with using memset is that in C++, a struct and a class are exactly the same thing except that by default, a struct has public visibility and a class has private visibility.

Thus, what if later on, some well meaning programmer changes MY_STRUCT like so:

struct MY_STRUCT
{
    int n1;
    int n2;

   // Provide a default implementation...
   virtual int add() {return n1 + n2;}  
};

By adding that single function, your memset might now cause havoc. There is a detailed discussion in comp.lang.c+