URGENT HELP REQUIRED

Hi, I'm a very young programmer...
I'm writing some source and i need it to be able to start timing on a
certain keystroke and end on a different, eg s=start c=cancel!

I have some ideas, and i can start the clock going, but have no
understanding of how to get the source to check to see is any more keys
have been struck so that it knows when to stop.

If i can find the source which tells the computer to read the time
without writing it I'll have it solved. CAN ANYONE HELP????

Thanx,
Matt
matt...@trumpet.com.au