Chagrined by admonishment for Re: Re: Re: signed bin2dec I thought I would try and improve.

I need to do 2 things:

  1. verify the input consisted of only '0's & '1's,
  2. capture which (0 or 1), the first character is.

It seemed natural to do this with a single regex and my first attempt was $string =~ m[^([01])+$] which failed.

There are several ways to fix it, but the manner in which this failed surprised me and whilst I know what it does, I'm not really sure that I can explain why. Any offers?

$_ =~ m[^([01])+$] and print "$_:'$1'" for qw[ 0 1 00 11 10 01 012];

0:'0'
1:'1'
00:'0'
11:'1'
10:'0'
01:'1'

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Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

In reply to Regex failure interpretation by BrowserUk

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