Check if UUID is in valid format

verify-uuid.php

<?php
/**
 * Check if a given string is a valid UUID
 * 
 * @param   string  $uuid   The string to check
 * @return  boolean
 */
function isValidUuid( $uuid ) {
    
    if (!is_string($uuid) || (preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid) !== 1)) {
        return false;
    }

    return true;
}

One line :)

/**
 * Check if a given string is a valid UUID
 * 
 * @param   mixed  $uuid   The string to check
 * @return  boolean
 */
function isValidUuid(mixed $uuid): bool
{    
    return is_string($uuid) && preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid);
}