(PHP 7, PHP 8)
IntlChar::isalnum — Check if code point is an alphanumeric character
$codepoint): ?bool
   Determines whether the specified code point is an alphanumeric character (letter or digit).  true for characters with general categories "L" (letters) and "Nd" (decimal digit numbers).
  
codepointLa valeur codepoint de type entier
(i.e. 0x2603 pour U+2603 SNOWMAN), ou le caractère encodé en UTF-8 de type chaîne de caractères
(i.e. "\u{2603}")
   Returns true if
   codepoint is an alphanumeric character, false if not. Returns null on failure.
  
Exemple #1 Test de différents codepoint
<?php
var_dump(IntlChar::isalnum("A"));
var_dump(IntlChar::isalnum("1"));
var_dump(IntlChar::isalnum("\u{2603}"));
?>
L'exemple ci-dessus va afficher :
bool(true) bool(true) bool(false)