Re: If there a way to find the location of the first difference between two strings?

Note that if the strings being compared are equal, both JavaFan and jwkrahn's solutions yield a number for the first difference offset that is equal to the length of the string(s).

>perl -wMstrict -lE
"my $s1 = 'abcdefg';
 my $s2 = 'abcdefg';
 ;;
 my $t = $s1 ^ $s2;
 ;;
 my ($f) = $t =~ /^(\x{00}*)/;
 say length $f;
 ;;
 $t =~ /^\0*/ && say $+[0];
"
7
7
[download]

Comment on Re: If there a way to find the location of the first difference between two strings? Download Code

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Re^2: If there a way to find the location of the first difference between two strings? by flexvault (Monsignor) on Mar 26, 2012 at 18:00 UTC
I still needed to know how they compare (lt eq gt), so I did the following: `srand( 711 ); . . . sub case2 { my $s1 = 'a' x 39 . 'b'; my $s2 = 'a' x 39 . chr( 98 + rand(4)); my ( $cmp, $loc ) = Cmp_and_Loc ( $s1, $s2 ); } sub Cmp_and_Loc { my ( $s1, $s2, undef ) = @_; my $t = 0; my $cmp = $s1 cmp $s2; if ( $cmp ) { $t = $s1 ^ $s2; $t =~ /^\0)/; $t = $+[0]; } return ( $cmp, $t ); }` [download] This appeared to work since if the strings are equal the sub returns 0,0. I will test your variation, but it still flies compared to anything I tried. Using the rand(4), I think I was able to test all combinations. As always, when someone shows you how to do it correctly, it becomes easy :-) Thank you "Well done is better than well said." - Benjamin Franklin*	[reply] [d/l]
Re^2: If there a way to find the location of the first difference between two strings? by trizen (Hermit) on Mar 26, 2012 at 17:50 UTC
Small fix: `$t =~ /[^\0]/ && say $-[0];`	[reply] [d/l]