use 5.010;
my $t = $s1 ^ $s2;
my ($f) = $t =~ /^(\x{00}*)/;
say length $f;

[download]

Another way to do that: 

use 5.010;
my $t = $s1 ^ $s2;
$t =~ /^\0*/ && say $+[0]

[download]

In reply to Re^2: If there a way to find the location of the first difference between two strings? by jwkrahn
in thread If there a way to find the location of the first difference between two strings? by flexvault

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