<?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

"☃"

• Second parameter of count function doesn't affect Countable
• Influence var_dump output of an object in PHP
• Change states of objects with SplObjectStorage

PHP 7.4, Zend 3.0, Symfony 4.3, Laravel 5.8, PHPUnit 8.0, Doctrine 2.10