(PHP 7, PHP 8)
IntlChar::isIDStart — Check if code point is permissible as the first character in an identifier
$codepoint): ?boolDetermines if the specified character is permissible as the first character in an identifier according to Unicode (The Unicode Standard, Version 3.0, chapter 5.16 Identifiers).
true for characters with general categories "L" (letters) and "Nl" (letter numbers).
codepointO valor int do ponto de código (por exemplo, 0x2603 para U+2603 SNOWMAN) ou o caractere codificado como uma string UTF-8 (por exemplo, "\u{2603}")
Returns true if
codepoint may start an identifier, false if not. Returns null on failure.
Exemplo #1 Testando diferentes pontos de código
<?php
var_dump(IntlChar::isIDStart("A"));
var_dump(IntlChar::isIDStart("$"));
var_dump(IntlChar::isIDStart("\n"));
var_dump(IntlChar::isIDStart("\u{2603}"));
?>
O exemplo acima produzirá:
bool(true) bool(false) bool(false) bool(false)
IntlChar::PROPERTY_ID_START