str_icontains and case-insensitive str_icontains

str_contains.php

<?php

// Polyfill for PHP 4 - PHP 7, safe to utilize with PHP 8

if (!function_exists('str_contains')) {
    function str_contains (string $haystack, string $needle)
    {
        return empty($needle) || strpos($haystack, $needle) !== false;
    }
}
// case-insensitive str_icontains
if (!function_exists('str_icontains')) {
    function str_icontains (string $haystack, string $needle)
    {
        return empty($needle) || stripos($haystack, $needle) !== false;
    }
}