IntlChar::isIDStart

(PHP 7)

Check if code point is permissible as the first character in an identifier

public static bool IntlChar::isIDStart ( mixed $codepoint )

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

Returns:

Returns TRUE if codepoint may start an identifier, FALSE if not.

Examples:

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)