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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

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:

This is Call By Reference

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:

11

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