Problem with vector::size_type

The size of a vector (and other STL containers) is given by its
size() function.

vector<string> vs;vector<string>::size_type siz = vs.size(); // The size of the vector.

Maybe you can post some code so we can see what's wrong.

Is it a vector of strings you want to concatenate?
Are you trying to turn the vector length ('it') into a string?
Are they C strings or C++ strings?
Where does size_type come into play?
What errors do you get?
Care to show some code?

I want to convert the length of the vector, as in number of objects, to an int. When I just use the size function, it says I have to have some other stuff.

I want to do some thing like this:

I'm not 100% sure what the problem is here, but it might be something else than the size() function that is the problem. This works however:

Can someone explain how iterators work?

They are like pointers. You increment them to move from one item in a container to the next. There's an STL link in my signature, and the documentation there contains a summary of iterators which might help you.