Using constructors in with vector::push_back()

You can do this:

vector<coords> x;x.push_back(coords(5.0, 5.3, -5.0));

as long as you define the appropriate coords constructor. (Please note that this code also calls the copy constructor for coords. This isn't an issue for a small 3D point class, but for bigger classes it might be.)

I got the constructer right I think;
I'll try it now

Quote:

Original post by Tron3k vector<coords> x;x.push_back(coords(5.0, 5.3, -5.0));

When you do something like that will a temporary object be created then copied, or will it be created in-place?

It will be created and copied. A temporary can only optimize out the copy operation when used in a function's return value, IIRC.

Something I wondered about is, if theres no default constructor, no destructor, no copy constructor and no assignment operator (I.e. its a primitive type), then the compiler should be able to construct it in place. I don't know what the standards say, but if theres no code going to be called as a result of creating, copting and destroying, then it may as well be constructed in place.
I'd test this, but I have MSVC 6.0, and its not exactly good at optimizing.