How to write this regular expression?

[Heiko Wundram]

On Wednesday 04 May 2005 11:34, could ildg wrote:
> Does it matter whether it is a homework?

Yes, it does matter. We're not your CS-class homework monkeys... :-) We're a 
forum of Python programmers who aid each other at thinking about solutions, 
we don't present solutions (normally), for a beautiful example of this, see 
the thread about finding similarities between two wave files...

But, anyway, as an additional hint: the stuff you need to do _can_ be solved 
by an RE (the language you're matching is actually regular if you impose 
several restrictions), but I'd rather not do it that way. Programming a small 
function which splits the string and then does the appropriate checks (by 
using int) should be much easier and faster.

And in case you really need an RE, watch this monster (to match a single term 
having numerical value >= 40)...

0*(([1-9][0-9]{2,})|([4-9][0-9]))

Matching numbers >= 31 isn't hard too, I leave this as an exercise to the 
reader... :-) But beware, I'd guess this regex performs rather poorly with 
respect to backtracking on erraneous input such as 
"00000000000000000000000030"...

--- Heiko.