(PHP 7, PHP 8)
IntlChar::isIDIgnorable — Check if code point is an ignorable character
$codepoint): ?boolDetermines if the specified character should be regarded as an ignorable character in an identifier.
   true for characters with general category "Cf" (format controls) as well as non-whitespace ISO controls (U+0000..U+0008, U+000E..U+001B, U+007F..U+009F).
  
Note:
Note that Unicode just recommends to ignore Cf (format controls).
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 ignorable in identifiers, false if not. Returns null on failure.
  
Exemple #1 Test de différents codepoint
<?php
var_dump(IntlChar::isIDIgnorable("A"));
var_dump(IntlChar::isIDIgnorable(" "));
var_dump(IntlChar::isIDIgnorable("\u{007F}"));
?>
L'exemple ci-dessus va afficher :
bool(false) bool(false) bool(true)
IntlChar::PROPERTY_DEFAULT_IGNORABLE_CODE_POINT