my @str = qw/ a.jpg b.gif c.png d.txt e.jpeg a.jpg.3 /;

for my $str (@str) {
  if ($str =~ /.*?\.(?!gif|jpe?g)/) {
    print "matched: $str\n";
  }
}

__END__

# output is
matched: c.png
matched: d.txt
matched: a.jpg.3
[download]

Thanks for the help, this is what I was trying to do. Works great, and it makes sense that the '?!' (whabang?) is at the start of the alternation.

An alternative is to use negative look behind... Your code was actually negative look ahead. To look behind, you need the < directive.



/(?<!\.gif)(?<!\.jpg)(?<!\.jpeg)$/
[download]

#!/usr/bin/perl -w
use strict;

my @string;
my $i;
$string[0]="http://www.server.com/image.jpg";
$string[1]="http://www.server.com/file.html";
$string[2]="http://www.serverjpg.com/image.jpg";
$string[3]="http://www.serverjpg.com/file.html";

for ($i=0; $i<4; $i++){
    if ($string[$i]=~/(.jpg|.gif|.jpeg)$/){
        print "Image\n";
    }
    else {
        print "No image\n";
    }
}
[download]