How can one ensure that the parameter passed to count() in PHP is an array or an object that implements Countable?

To ensure that the parameter passed to count() in PHP is an array or an object that implements Countable, you can use the is_array() function to check if the parameter is an array, and the instanceof operator to check if it is an object that implements the Countable interface. By performing these checks before calling the count() function, you can prevent errors and ensure that the function operates as expected.

function customCount($param) {
    if (is_array($param) || $param instanceof Countable) {
        return count($param);
    } else {
        return 'Parameter must be an array or an object that implements Countable interface.';
    }
}

// Example usage
$array = [1, 2, 3];
echo customCount($array); // Output: 3

$obj = new ArrayObject([1, 2, 3]);
echo customCount($obj); // Output: 3

$string = 'Hello';
echo customCount($string); // Output: Parameter must be an array or an object that implements Countable interface.