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<?php $dowISO = 7; $weekdayISO = (new DateTime('Monday')) ->add(new DateInterval('P' . ($dowISO - 1) . 'D')); echo $dowISO . ' = ' . $weekdayISO->format('l');
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.4, 8.3.6 - 8.3.7
7 = Sunday
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 7 = Sunday

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