[TriLUG] YAPQ (yet another perl question)..

[Kevin Hunter]

At 3:24pm -0400 on Thu, 11 Jun 2009, Greg Brown wrote:
> so close:
> 
> 15998976 bytes total (8083968 bytes free)
> routername#Total bytes: 15998976
> Free bytes:  8
> 
> so it's picking up the total bytes but on the free bytes it's only picking
> up the last digit of the total free.

This is because operators, for performance reasons, are "greedy" unless
told otherwise.  So, the '.*' is matching as much as possible before it
lets the [0123456789]+ match.  To correct it, I'd suggest being 100%
explicit in what you want:

>> $string =~ m/([0123456789]+) bytes total.*([0123456789]+) bytes free/;

$string =~ m/^(\d+) bytes total \((\d+) bytes free/;
   or
$string =~ m/^(\d+) bytes total.*?(\d+) bytes free/;

^ - Make sure to start the match at the beginning of the line
\d - shorthand for [0123456789]
* - match preceding character as many times as possible
*? - match preceding character as few times as possible

I'd suggest the first form, as it's more explicit.  Most folks can't
read regular expressions, so wherever possible, I suggest you make them
as simple *and explicit* as you can.

Cheers,

Kevin