Generally:

$variable =~ m/;=(\d+);/
print $1;  #holds 99 now.
[download]

So everything between parens gets assigned to variables with a number as the name. They stay available until the next match or substitution. You can read all about it in perlop and perlre.

Hope this helps,

Jeroen
"We are not alone"(FZ)
Update: chromatic pointed out to me that it would be good to make the remark that $1 is only set when the string matches. I totally agree with him.