PHP regex to check if a string ends with a space and 15 other characters

I’m looking for a PHP regex to check if a string ends with a string that

• starts with a space
• then 15 characters which contain only 0-9 and a-f characters (lower case)

Match:

$myString = "something here 62ffe537a66ddcf"; // space after "here" and then 15 characters

No Matches:

$myString1 = "something here62ffe537a66ddcf"; // space missing before the 6
$myString2 = "something here 62ffe537a66ddc"; // only 15 characters (including the space)
$myString3 = "something here 62ffe537A66ddC"; // contains upper case characters

My attempt. There might be a shorter way?

$myString = "something here 62ffe53766ddcf"; // space after "here" and then 15 characters
if (stringEndsWithId($myString)) {
    echo "string ends with id";
}
else {
    echo "string does not end with id";
}

function stringEndsWithId($str) {

    if (str_starts_with(right($str, 16) , ' ')) {
        return preg_match('/[^a-f0-9]/', $str);

    }

    return false;

}

function right($string, $count) {
    return substr($string, strlen($string) - $count, $count);
}

>Solution :

You can use [0-9a-f] to match any of the 0-9 and a-f chars, followed by {15} to match exactly 15 of them, followed by $ to match the end of the string.

function stringEndsWithId($str) {
    return ( preg_match('/ [0-9a-f]{15}$/', $str) );
}