The problem is context. The match operator /.../ returns various things depending on the presence of the /g modifier and the context, see perlop.

In particular, you need to enforce list context somehow if you want the matching to return the matched part. So, use something like 

sort { ($a =~ /(\d+)/)[0] <=> ($b =~ /(\d+)/)[0] }
sort { ($a =~ /\d+/g)[0]  <=> ($b =~ /\d+/g)[0]  }
sort { (split /;/, $a)[0] <=> (split /;/, $b)[0] }

[download]

It might be nicer to use the Schwartzian Transform or Orcish Maneuvre to avoid repeated matching: 

# ST
my @sorted = map  $_->[1],
             sort { $a->[0] <=> $b->[0] }
             map  [ (split /;/)[0], $_], 
             @lines;

# OM
use Syntax::Construct qw{ // };
my %cache;
my @sorted = sort {
                 $cache{$a} //= (split /;/, $a)[0]
                 <=>
                 $cache{$b} //= (split /;/, $b)[0]
             } @lines;

[download]

Or, if you don't mind some warnings about non-numeric values, just compare the strings numerically directly: 

sort { $a <=> $b } @lines

[download]

(All code untested.)

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: Sorting file rows and copy them in an array by choroba
in thread Sorting file rows and copy them in an array by savio

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