PHP: add optional parameters to a function

<?php // The optional parameters are given default values in the function declaration function testOptionalParameters($first = 1, $second = 2, $third = 3) { echo "$first, $second, $third" . PHP_EOL; } testOptionalParameters(); // Prints 1, 2, 3 testOptionalParameters(6); // Prints 6, 2, 3 testOptionalParameters(6, 7); // Prints 6, 7, 3 testOptionalParameters(6, 7, 8); // Prints 6, 7, 8 // Can't skip an optional parameter to get its default value; syntax error: testOptionalParameters(, 7, 8);