Write a PHP program to find a single number in an array that doesn't occur twice

<?php
function single_number($arr)
{
 
    $result = $arr[0];
    
    for($i=1;$i<sizeof($arr);$i++)
    {
        $result = $result ^ $arr[$i];
    }    
 return $result;

}
$arr1 = array(5, 3, 4, 3, 4);
$arr2 = array(3, 2, 5, 2, 1, 5, 3);
print_r($arr1);
print_r('Single Number: '.single_number($arr1)."\n");
print_r($arr2);
print_r('Single Number: '.single_number($arr2)."\n");
?>

Sample Output:

Array                                                       
(                                                           
    [0] => 5                                                
    [1] => 3                                                
    [2] => 4                                                
    [3] => 3                                                
    [4] => 4                                                
)                                                           
Single Number: 5                                            
Array                                                       
(                                                           
    [0] => 3                                                
    [1] => 2                                                
    [2] => 5                                                
    [3] => 2                                                
    [4] => 1                                                
    [5] => 5                                                
    [6] => 3                                                
)                                                           
Single Number: 1