Finding a string in an other string, then..

From: Joel (joel_at_hotmail.ru)
Date: 02/28/04 

Date: Sat, 28 Feb 2004 13:46:22 +0300

I have a text $alltext, and want to find a specific string
$stringtofind that is in the text.

Then, I want the script to read a number that is right after the
string.

What is the best way to get it ?

Thanks !