Online PHP editor | output for QtdhK

<?php $numbers = ['one', 'two', 'three']; // Normal foreach loop, no reference used foreach ($numbers as $number) { // Does not affect the original array, only modifies // $number within the scope of the loop $number = strtoupper($number); } // Will dump unmodified array: ['one', 'two', 'three'] var_dump($numbers); // Foreach loop by reference foreach ($numbers as &$number) { // $number is a reference so the corresponding // value in $numbers is also updated $number = strtoupper($number); } // Will dump: ['ONE', 'TWO', 'THREE'] var_dump($numbers);