Algori...MXX_002(3pm)

✨ Algori...MXX_002(3pm) ✨

okay so bestie, you found the Algori...MXX_002(3pm) page — it lives in the User Contributed Perl Documentation and it's tiny, it's focused, it's giving "one job, done flawlessly" 💅. Underneath that abbreviated title is CheckDigits::MXX_002, and no cap, she only does one thing, but she EATS at it 👑

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🌸 NAME

CheckDigits::MXX_002 — compute check digits for CAS 🧪

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🎀 SYNOPSIS

use Algorithm::CheckDigits;

$cas = CheckDigits('cas');

if ($cas->is_valid('1333-74-0')) {
      # do something
}

$cn = $cas->complete('1333-74-');
# $cn = '1333-74-0'

$cd = $cas->checkdigit('1333-74-0');
# $cd = '0'

$bn = $cas->basenumber('1333-74-0');
# $bn = '1333-74-'

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💖 DESCRIPTION

🧚 ALGORITHM

lowkey the whole thing is three steps, like a little recipe 👩‍🍳

1. Beginning right with the second digit all digits are weighted ascending starting with 1. (yes, second digit, from the right — read it again, it's not the first one, iykyk 🫶)
2. The sum of those products is computed. Just multiply, then add, bestie. Math ate 💅
3. The checksum is the last digit of the sum from step 2 (modulo 10). So like, sum % 10, periodt.

💅 METHODS

• is_valid($number) — Returns true only if $number consists solely of numbers and the last digit is a valid check digit according to the algorithm given above. Returns false otherwise.
• complete($number) — The check digit for $number is computed and concatenated to the end of $number. Returns the complete number with check digit, or '' if $number does not consist solely of digits and spaces. 🙈
• basenumber($number) — Returns the basenumber of $number if $number has a valid check digit. Return '' otherwise.
• checkdigit($number) — Returns the checkdigit of $number if $number has a valid check digit. Return '' otherwise.

not me noticing the first one says "numbers" while the second one says "digits and spaces" 👀 that's just how the page tells it, so that's how I'm telling it. Keep your inputs clean either way 💖

🌈 EXPORT

None by default. Like, nothing gets exported, zero, zilch, not even one function sneaking out the door. You call it through CheckDigits, that's the whole vibe.

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👑 AUTHOR

Mathias Weidner, <mamawe@cpan.org> — legend behavior, honestly 🫶

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🦋 THANKS

Aaron W. West pointed me to a fault in the computing of the check digit. (a real one, bestie — public credit, we love to see it 💀✨)

HERMIER Christophe made me aware that CAS is now assigning 10-digit CAS Registry Numbers (http://www.cas.org/newsevents/10digitrn.html) — glow up for CAS, and a heads up for anyone coding against the old length, fr fr.

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⭐ SEE ALSO

• perl 🐪
• CheckDigits
• www.pruefziffernberechnung.de
• www.cas.org
• http://www.cas.org/expertise/cascontent/registry/checkdig.html

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and that's the page 🎀 it's perl v5.36.0, stamped 2022-10-13, and the whole thing is filed under the title Algori...MXX_002(3pm). stay checksummed, bestie, byeee 🫶💜