PHP Call By Reference PHP

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

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.

1. <?php  
2. function adder(&$str2)  
3. {  
4.     $str2 .= 'Call By Reference';  
5. }  
6. $str = 'This is ';  
7. adder($str);  
8. echo $str;  
9. ?>  

Output:

Example 2

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

1. <?php  
2. function increment(&$i)  
3. {  
4.     $i++;  
5. }  
6. $i = 10;  
7. increment($i);  
8. echo $i;  
9. ?>  

Output: