PHP Manual: Check whether the code point is defined

public static boolnull IntlChar::isdefined(intstring $codepoint)

Determines whether the specified code point is "defined", which usually means that it is assigned a character.

true for general categories other than "Cn" (other, not assigned).

Note:
Note that non-character code points (e.g., U+FDD0) are not "defined" (they are Cn), but surrogate code points are "defined" (Cs).

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}")

Returns true if codepoint is a defined character, false if not. Returns null on failure.

Example #1 Testing different code points

<?php
var_dump(IntlChar::isdefined("A"));
var_dump(IntlChar::isdefined(" "));
var_dump(IntlChar::isdefined("\u{FDD0}"));
?>

The above example will output:

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

IntlChar::isdefined