integer to string

Okay, this can't possibly be so hard. I'm trying to convert an integer to a string, which then gets appended to another string. I've found itoa but the problem with itoa is that it actually converts an integer to a character array instead of to a string. Normally with strings it's possible to write something like:

string string1 = "hi";
string string2 = " there";
string string3 = string1 + string2;

However, because itoa returns a characterArray -- I'll call it foo - I can't then use: string3 = string1 + foo;
which is what I need to do.

There are several things that would help. If I could create a string from a character array, I'd be set. So far, I've only been able to find out how to convert a string into a character array. I've gone over this page:
http://www.msoe.edu/eecs/cese/resources/stl/string.htm

Okay, there's probably something really obvious I'm missing...