Algori...M23_002(3pm)

💖 Algori...M23_002(3pm) — CheckDigits::M23_002 💖

okay bestie, welcome to the User Contributed Perl Documentation for CheckDigits::M23_002, aka the module that lives inside Algorithm::CheckDigits and handles your Irish TIN checksum math. yes, you can ship this to prod. no, you don't need to read it twice. let's go 🦋

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✨ NAME ✨

CheckDigits::M23_002 — compute check digits for Tax Identification Number (IE) 🎀

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✨ SYNOPSIS ✨

use Algorithm::CheckDigits;

$dni = CheckDigits('tin_ie');

if ($dni->is_valid('8473625E')) {
      # do something
}

$cn = $dni->complete('1234567.W');
# $cn = '1234567TW'

$cd = $dni->checkdigit('1234577IA');
# $cd = 'I'

$bn = $dni->basenumber('1234577WW');
# $bn = '1234577.W'

like. look at that. it just works 💅

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✨ DESCRIPTION ✨

🌸 ALGORITHM 🌸

so the Irish TIN — that's the Tax Identification Number, the same lil guy you might know as the VAT Regstration Number — is built like this: 7 digits, then a letter in the range from 'A' - 'W' as checksum, and then an optionally letter in the range from 'A' - 'I' or the letter 'W'. yes, "an optionally letter." she's quirky. we respect her. 👑

here's the whole ritual:

1. In reverse order, each digit is multiplied by a weight started at 2. (i.e. the number left from the check digit is multiplied with 2, the next with 3 and so on). 🌀
2. If there is an optional letter following the checksum letter (position 9), this letter is mapped to a numeric value based on the following mapping: "A" = 1, "B" = 2, ... "H" = 8, "I" = 9. "W" or absence of this letter means a value of 0. This numeric value is multiplied with 9. 🔢
3. All products from step 1 and 2 are added. ➕
4. The check digit is the sum from step 3 modulo 23. This number is expressed as the corresponding letter from the alphabet where A-V correspond to 1-22 and W stands for check digit 0. and that's the tea ☕

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🫶 METHODS 🫶

🌟 is_valid($number)

Returns true only if $number complies with the rules given above and there is a valid check digit at position eight.

Returns false otherwise.

(no cap, that's the whole vibe check 🕵️♀️)

🌟 complete($number)

The check digit for $number is computed and inserted at position eight of $number.

Returns the complete number with check digit or '' if $number does not consist solely of digits and an optional letter at position nine.

🌟 basenumber($number)

Returns the basenumber of $number if $number has a valid check digit. As a placeholder for the checksum a point (.) is inserted at position eight when the checksum contains the optional letter at position nine.

Return '' otherwise.

🌟 checkdigit($number)

Returns the checkdigit of $number if $number has a valid check digit.

Return '' otherwise.

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🧚 EXPORT 🧚

None by default. nothing jumps out at you uninvited bestie, she's respectful like that 💜

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✨ AUTHOR ✨

Mathias Weidner, "<mamawe@cpan.org>" 🫡 iconic behavior, thank you for your service

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✨ SEE ALSO ✨

• perl
• CheckDigits
• https://ec.europa.eu/taxation_customs/tin/

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and that's the page, fr fr 🌈 this one's from perl v5.36.0, dated 2022-10-13 — so go forth, validate those TINs, and remember: mod 23 never misses. slay 💖✨🎀