Threading is not defined in C++.
The threading models of e.g. Linux and Windows are a bit different,
so you need a platform specific solution or use a library has a
uniform interface for different platforms. Such a solution may
not be portable to all platforms with a standard C++ compiler.
Take a look at boost. As Fred Zwarts told you, threading is not part
of the current C++ standard. But the next standard will include
threading, and boost should be a close approximation to what is going
to be in the next standard.
/Peter