cprToBirthdate(string $cpr): ?string
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May 25, 2021 08:58
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Calculate the full birthdate given a CPR number.
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<?php | |
declare(strict_types=1); | |
/** | |
* Calculate the full birthdate given a CPR number. | |
* The logic is described in this document. | |
* | |
* @see https://cpr.dk/media/12066/personnummeret-i-cpr.pdf | |
* @param string $cpr | |
* @return string|null format:Y-m-d | |
*/ | |
function cprToBirthdate(string $cpr): ?string | |
{ | |
if (!is_numeric($cpr) || !$cpr || strlen($cpr) !== 10) { | |
return null; | |
} | |
$day = $cpr[0] . $cpr[1]; | |
$month = $cpr[2] . $cpr[3]; | |
$year = $cpr[4] . $cpr[5]; | |
$seventh = (int) $cpr[6]; | |
switch ($seventh) { | |
case 0; | |
case 1; | |
case 2; | |
case 3; | |
$century = '19'; | |
break; | |
case 4; | |
case 9: | |
$century = (int) $year <= 36 | |
? '20' | |
: '19'; | |
break; | |
case 5; | |
case 6; | |
case 7; | |
case 8; | |
$century = (int) $year <= 57 | |
? '20' | |
: '18'; | |
break; | |
default: | |
return null; | |
} | |
$fullYear = $century . $year; | |
if (!checkdate((int) $month, (int) $day, (int) $fullYear)) { | |
return null; | |
} | |
return "{$fullYear}-{$month}-{$day}"; | |
} |
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<?php | |
declare(strict_types=1); | |
require_once '../functions.php'; | |
use PHPUnit\Framework\TestCase; | |
final class CprToBirthdateTest extends TestCase | |
{ | |
/** | |
* @covers ::cprToBirthdate | |
* @dataProvider casesProvider | |
*/ | |
public function testCases(string $cpr, ?string $birthdate): void | |
{ | |
self::assertSame($birthdate, cprToBirthdate($cpr)); | |
} | |
public function casesProvider(): array | |
{ | |
return [ | |
// Test edges of all the defined combinations of | |
// the 5th, 6th and 7th digit. | |
// 0 | |
['2412000000', '1900-12-24'], | |
['2412990000', '1999-12-24'], | |
// 1 | |
['2412001000', '1900-12-24'], | |
['2412991000', '1999-12-24'], | |
// 2 | |
['2412002000', '1900-12-24'], | |
['2412992000', '1999-12-24'], | |
// 3 | |
['2412003000', '1900-12-24'], | |
['2412993000', '1999-12-24'], | |
// 4 | |
['2412004000', '2000-12-24'], | |
['2412364000', '2036-12-24'], | |
['2412374000', '1937-12-24'], | |
['2412994000', '1999-12-24'], | |
// 5 | |
['2412005000', '2000-12-24'], | |
['2412575000', '2057-12-24'], | |
['2412585000', '1858-12-24'], | |
['2412995000', '1899-12-24'], | |
// 6 | |
['2412006000', '2000-12-24'], | |
['2412576000', '2057-12-24'], | |
['2412586000', '1858-12-24'], | |
['2412996000', '1899-12-24'], | |
// 7 | |
['2412007000', '2000-12-24'], | |
['2412577000', '2057-12-24'], | |
['2412587000', '1858-12-24'], | |
['2412997000', '1899-12-24'], | |
// 8 | |
['2412008000', '2000-12-24'], | |
['2412578000', '2057-12-24'], | |
['2412588000', '1858-12-24'], | |
['2412998000', '1899-12-24'], | |
// 9 | |
['2412009000', '2000-12-24'], | |
['2412369000', '2036-12-24'], | |
['2412379000', '1937-12-24'], | |
['2412999000', '1999-12-24'], | |
// Make sure all parts are padded with zero | |
['0101010000', '1901-01-01'], | |
// Invalid cases | |
['', null], | |
['0000000000', null], | |
'Invalid length' => ['010101000', null], | |
'Must be only digits' => ['0101a10000', null], | |
'Invalid day' => ['3201010000', null], | |
'Invalid month' => ['0113010000', null], | |
]; | |
} | |
} |
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