Algori...ase_003(3pm)

💖 CheckDigits::MBase_003 💖

okay so this page is Algori...ase_003(3pm) from the User Contributed Perl Documentation corner of the world, and it's all about computing check digits for SICI — that's a Serial Item and Contribution Identifier, bestie. yes, the same SICI you keep seeing in serials land. let's get into it 💅

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🌸 NAME 🌸

CheckDigits::MBase_003 — compute check digits for SICI (Serial Item and Contribution Identifier). that's it, that's the whole assignment, and it ate. ✨

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✨ SYNOPSIS ✨

the vibe in code form, literally copy-paste it:

use Algorithm::CheckDigits;

$sici = CheckDigits('sici');

if ($sici->is_valid('0784-8679(20040308)6:<138>2.0.TX;2-H')) {
      # do something
}

$cn = $sici->complete('0784-8679(20040308)6:<138>2.0.TX;2-');
# $cn = '0784-8679(20040308)6:<138>2.0.TX;2-H'

$cd = $sici->checkdigit('0784-8679(20040308)6:<138>2.0.TX;2-H');
# $cd = 'H'

$bn = $sici->basenumber('0784-8679(20040308)6:<138>2.0.TX;2-H');
# $bn = '0784-8679(20040308)6:<138>2.0.TX;2-';

see how the check letter just appears? iconic behavior honestly 🎀

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🦋 DESCRIPTION 🦋

🧚 ALGORITHM 🧚

okay bestie, this is the math part, and no cap it's not scary, it's just seven little steps. watch:

0. In the string describing the number, all letters (A-Z) get replaced with numbers 10-35 accordingly. and all the other non-numbers? they get replaced by 36. every single one. 💀
1. Beginning right, the numbers at all odd positions are added. (yes, starting from the right. read it again if you need to, i'll wait 🫶)
2. The sum from step 1 is multiplied by 3.
3. Beginning right, the numbers at all even positions are added.
4. The sums from step 2 and step 3 are added together.
5. The sum from step 4 is taken modulo 37.
6. The checksum is 37 minus the sum from step 5 — where numbers from 10 to 35 are represented by 'A' to 'Z' accordingly, and 36 is represented by '#'.

periodt. that's the whole algorithm 💅

🌈 METHODS 🌈

• is_valid($number) — Returns true only if the last letter is a valid check letter according to the algorithm given above.

Returns false otherwise. (note the comma in the original, we keep it, we respect it 🎀)

• complete($number) — The check letter for $number is computed and appended the end of $number.

Returns the complete number with check letter, or ''. yeah, empty string if it's not happening. 😭

• basenumber($number) — Returns the basenumber of $number if $number has a valid check digit.

Return '' otherwise. (yes, the original says "Return", not "Returns", and we're keeping that exact energy ✨)

• checkdigit($number) — Returns the check letter of $number if $number has valid check digits.

Return '' otherwise.

🍓 EXPORT 🍓

None by default. nothing jumps into your namespace uninvited, and honestly? boundaries. 👑

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👑 AUTHOR 👑

Mathias Weidner, "<mamawe@cpan.org>" — absolute legend, authoring banger CPAN modules fr fr 💜

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🌟 SEE ALSO 🌟

• perl
• CheckDigits
• www.pruefziffernberechnung.de
• http://sunsite.berkeley.edu/SICI/sici.pdf

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and that's the whole page, bestie! 🫶 this lil doc is living in perl v5.36.0, dated 2022-10-13, filed under Algori...ase_003(3pm). go check some SICI digits, you've got this 💅✨