Reference Parameters in PHP

It is possible to make a change to a function parameter lead to a change of the parameter outside the function. To do this, the function parameter should be declared as a reference:

<?php
	function func(&$num)
	{
		$num = 2;
	}
	
	$num = 1;
	func($num);
	echo $num; // 2
?>

Correct the following code so that the variable changes inside the function:

<?php
	$num = 1;
	
	function func($num)
	{
		$num++;
	}
	
	func($num);
	echo $num; // should output 2
?>

Correct the following code so that the array changes inside the function:

<?php
	$arr = [1, 2, 3, 4, 5];
	
	function func($arr)
	{
		$arr[0] = '!';
	}
	
	func($arr);
	var_dump($arr);
?>