php refers to the problem of changing the value of a variable

 
<?php 
$foo = 'Bob'; //  will  'Bob'  Assigned to  $foo 
$bar = &$foo; //  through  $bar  reference  $foo 
echo $foo.'<br/>'; 
$bar = "My name is $bar"; //  Modify the  $bar  variable  
echo $bar.'<br/>'; 
echo $foo.'<br/>'; // $foo  The value of  
?> 

Output:
Bob
My name is Bob
My name is Bob
We see that the original value does change, after the reference and the assignment, but before the assignment the original variable does not change