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.

Example 1

<?php

function adder(&$str2)

{

$str2 .= 'Call By Reference';

}

$str = 'This is ';

adder($str);

echo $str;

Output:

This is Call By Reference

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.

Example 2

<?php

function increment(&$i)

{

$i++;

}

$i = 10;

increment($i);

echo $i;

Output: