PHP Call By Reference

In case of PHP call by reference, actual value is modified if it is modified inside the function. In such case, you need to use & (ampersand) symbol with formal arguments. The & represents reference of the variable. Let's understand the concept of call by reference by the help of examples.

In this example, variable $str is passed to the adder function where it is concatenated with 'Call By Reference' string. Here, printing $str variable results 'This is Call By Reference'. It is because changes are done in the actual variable $str.

            
<?php  
function adder(&$str2)  
{  
$str2 .= 'Call By Reference';  
}  
$str = 'This is ';  
adder($str);  
echo $str;  
?>  
            

Let's understand PHP call by reference concept through another example.

<?php  
function increment(&$i)  
{  
    $i++;  
}  
    $i = 10;  
    increment($i);  
    echo $i;  
?>