Re: Tri state string compare? (Solved! see update2)

There's something missing in that solution, or I don't understand it. I'd have expected something like:

use strict;
use warnings;

my $abc = 'AABCBAABCCCCAB';
my $yes = 'AABABAABABABAB';
my $no1 = 'ABBABAABABABAB';
my $no2 = 'ABBABAABABAB';

$abc =~ tr/AB/\0/c;

print +(($abc & $_) eq $abc) ? "$_: yes\n" : "$_: no\n" for $yes, $no1
+, $no2;
[download]

Prints:

AABABAABABABAB: yes
ABBABAABABABAB: no
ABBABAABABAB: no
[download]

The test fails if you change all the Bs to Es of course.

Premature optimization is the root of all job security

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Re^2: Tri state string compare? (Solved! see update2) by BrowserUk (Patriarch) on Dec 13, 2015 at 21:19 UTC
There's something missing in that solution, or I don't understand it Does the fact that I know all my strings will be equal length explain things? Here's my test code: #! perl -slw use strict; my $pat = 'AAAAAAABCCCCCCCCABAAAAAAA'; my @set = ( 'AAAAAAABAAABABBBABAAAAAAA', 'AAAAAAABAAABBABBABAAAAAAA', 'AAAAAAABAAABBBABABAAAAAAA', 'AAAAAAABBAAABABBABAAAAAAA', 'AAAAAAABBAAABBABABAAAAAAA', 'AAAAAAABBBAAABABABAAAAAAA', 'ABAAAAABAAABABBBABAAAAAAA', 'AAAAAAAAAAABBABBABAAAAAAA', 'AAAAAAABAAABBBABAABAAAAAA', 'AAAAAAABBAAABABBABAAAAAAA', 'AAAAABABBAAABBABAAAAAAAAA', 'AAAAAAABBBAAABABAAAAAAAAA', ); for my $test ( @set ) { printf "$pat\n$test\n%s %s\n\n", $pat & $test, ( $pat & $test ) eq + $test ? 'OK' : 'NO'; } __END__ C:\test>junk77 AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABAAABABBBABAAAAAAA AAAAAAABAAABABBBABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABAAABBABBABAAAAAAA AAAAAAABAAABBABBABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABAAABBBABABAAAAAAA AAAAAAABAAABBBABABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABBAAABABBABAAAAAAA AAAAAAABBAAABABBABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABBAAABBABABAAAAAAA AAAAAAABBAAABBABABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABBBAAABABABAAAAAAA AAAAAAABBBAAABABABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA ABAAAAABAAABABBBABAAAAAAA A@AAAAABAAABABBBABAAAAAAA NO AAAAAAABCCCCCCCCABAAAAAAA AAAAAAAAAAABBABBABAAAAAAA AAAAAAA@AAABBABBABAAAAAAA NO AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABAAABBBABAABAAAAAA AAAAAAABAAABBBABA@@AAAAAA NO AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABBAAABABBABAAAAAAA AAAAAAABBAAABABBABAAAAAAA OK AAAAAAABCCCCCCCCABAAAAAAA AAAAABABBAAABBABAAAAAAAAA AAAAA@ABBAAABBABA@AAAAAAA NO AAAAAAABCCCCCCCCABAAAAAAA AAAAAAABBBAAABABAAAAAAAAA AAAAAAABBBAAABABA@AAAAAAA NO [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^2: Tri state string compare? (Solved! see update2) by Anonymous Monk on Dec 13, 2015 at 22:25 UTC
A bit more digestible explanation (imo): `$ perl -e 'printf "$_ => %b\n", ord($_) for qw( A B C @ )' A => 1000001 B => 1000010 C => 1000011 @ => 1000000` [download] so, `"A" & "B" (0b1000001 & 0b1000010)` yields `"@" (0b1000000)`, `"A" & "C" (0b1000001 & 0b1000011)` yields `"A" (0b1000001)`, `"B" & "C"` yields `"B"`. So, for example: `"ABC" & "ABA" => "ABA" "ABB" & "ABA" => "AB@" "ABC" & "AB" => "AB" # perlop: "the & op acts as though the longer operand # were truncated to the length of the shorter" # so the strings don't have to be equal length # for that to work` [download]	[reply] [d/l] [select]
Re^3: Tri state string compare? (Solved! see update2) by GrandFather (Saint) on Dec 13, 2015 at 22:53 UTC
Yes, I was being thick. The penny dropped 30s after seeing BUK's reply. Premature optimization is the root of all job security	[reply]
Re^4: Tri state string compare? (Solved! see update2) by Anonymous Monk on Dec 13, 2015 at 23:03 UTC
Yeah, I thought you probably didn't need explanations, but decided to write anyway, because someone else might find it useful :)	[reply]
Re^3: Tri state string compare? (Solved! see update2) by BrowserUk (Patriarch) on Dec 13, 2015 at 23:19 UTC
A bit more digestible explanation (imo): IMO also :) With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^3: Tri state string compare? (Solved! see update2) by Anonymous Monk on Dec 13, 2015 at 22:29 UTC
so the strings don't have to be equal length for that to work oops! of course, that would work only if the test string shorter that the tested string	[reply]