C memset seems to not write to every member

Question

I wrote a small coordinate class to handle both int and float coordinates.

template 
class vector2
{
public:
    vector2() { memset(this, 0, s         


        

Answer 1

Don't use memset. It'll break horribly on non-POD types (and won't necessarily be easy to debug), and in this case, it's likely to be much slower than simply initializing both members to zero (two assignments versus a function call).

Moreover, you do not usually want to zero out all members of a class. You want to zero out the ones for which zero is a meaningful default value. And you should get into the habit of initializing your members to a meaningful value in any case. Blanket zeroing everything and pretending the problem doesn't exist just guarantees a lot of headaches later. If you add a member to a class, decide whether that member should be initialized, and how.

If and when you do want memset-like functionality, at least use std::fill, which is compatible with non-POD types.

If you're programming in C++, use the tools C++ makes available. Otherwise, call it C.