Constructor syntax

From: Ben R. (BenR_at_discussions.microsoft.com)
Date: 11/01/04 

Date: Mon, 1 Nov 2004 12:37:02 -0800

Could someone explain to me this odd syntax for a class constructor
definition header where after the definition, there's a ":" and calls to what
look like functions but are just variables? Example:
class myclass{
myclass(int howmany) : somevar(5)
{
// constructor goes here
};

I think I reproduced it accurately. I see this syntax every now and then and
would just like a better understanding of it. Does it just assign the value 5
to somevar? If so, what's the advantage here? Any clarification would be
appreciated. Thanks...

-Ben