#!/usr/bin/perl

use strict;  
use warnings;

my $str = "1" x 5;

$_ = $str;
print "Single s///g:\n";
print "Before: [$_]; ";
s/1(1+)/$1/g;
print "After [$_]\n";

$_ = $str;
print "Loop s///:\n";
while (1) {
    print "Before: [$_]; "; 
    last unless s/1(1+)/$1/;
    print "After: [$_]\n";
}
print "\n";

__END__
Single s///g:
Before: [11111]; After [1111]
Loop s///:
Before: [11111]; After: [1111]
Before: [1111]; After: [111]
Before: [111]; After: [11]
Before: [11]; After: [1]
Before: [1];