<?php

dump(
    IntlChar::toupper('ä'),
    IntlChar::tolower('Č'),
    IntlChar::totitle('f'),

    IntlChar::isUUppercase('A'),
    IntlChar::isULowercase('A'),
    
    IntlChar::charName('Ü'),
    
    IntlChar::isdigit(3),
    IntlChar::isdigit('3'),
    IntlChar::isdigit(0xFF),
    IntlChar::isdigit(0b01),
    
    "\u{2603}"
);

^ "Ä"

^ "č"

^ "F"

^ true

^ false

^ "LATIN CAPITAL LETTER U WITH DIAERESIS"

^ false

^ true

^ false

^ false

^ "☃"

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PHP 8.0, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8