reusing parts of a string in RE matches?

[John Salerno]

BartlebyScrivener wrote:
> Right about now somebody usually jumps in and shows you how to do this
> without using regex and using string methods instead.
> 
> I'll watch.
> 
> rd
> 

Heh heh, I'm sure you're right, but this is more just an exercise for me 
in REs, so I'm curious how you might do it, unless the answer is that 
it's just too complicated to be worth it (like Murali's example!) That 
goes beyond just an RE pattern.