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<IntlChar::isIDPartIntlChar::isISOControl>
^IntlCharLast updated: Mon, 26 Oct 2026

IntlChar::isIDStart

(PHP 7, PHP 8)

IntlChar::isIDStart — Check if code point is permissible as the first character in an identifier

Description

public static function IntlChar::isIDStart(int|string $codepoint): ?bool

Determines 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).

Parameters

codepoint

The int codepoint value (e.g. 0x2603 for U+2603 SNOWMAN), or the character encoded as a UTF-8 string (e.g. "\u{2603}")

Return Values

Returns true if codepoint may start an identifier, false if not. Returns null on failure.

Examples

Example #1 Testing different code points

<?php
var_dump(IntlChar::isIDStart("A"));
var_dump(IntlChar::isIDStart("$"));
var_dump(IntlChar::isIDStart("\n"));
var_dump(IntlChar::isIDStart("\u{2603}"));
?>

The above example will output:

bool(true)
bool(false)
bool(false)
bool(false)

See Also


<IntlChar::isIDPartIntlChar::isISOControl>
^IntlCharLast updated: Mon, 26 Oct 2026