$reference_var1 = &$reference_var2;
Here both the variable, that is, $reference_var1 and $reference_var2 are equal.
You can say, both variable point to the same place.
Let's take an example that demonstrates reference in PHP.
<html> <head> <title>PHP Reference Example</title> </head> <body> <?php $num1 = 10; $num2 = &$num1; $sum = $num1 + $num2; echo $sum; ?> </body> </html>
Below is the sample output produced by the above reference example code in PHP.
If you assign the reference of any variable say $first_ref_var to a another variable say $second_ref_var, then if you change the value of variable $first_ref_var, the $second_ref_var's value will also be changed automatically, as you have assigned the reference of that variable.
Let's take another example to understand about the main use of reference in PHP.
<html> <head> <title>Reference example in PHP</title> </head> <body> <?php echo "With Reference:<br/>"; // initialize first variable with value $num1 = 10; // initialize the reference of first variable to second variable $num2 = &$num1; $sum = $num1 + $num2; echo $sum; echo "<br/>"; // change the value of first variable $num1 = 20; echo $num1; echo "<br/>"; // you will see, the value of second variable will also be changed // this is the benefit of using reference in PHP echo $num2; echo "<hr/>"; echo "Without Reference:<br/>"; $var1 = 10; $var2 = $var1; $add = $var1 + $var2; echo $add; $var1 = 20; echo "<br/>"; echo $var1; echo "<br/>"; echo $var2; ?> </body> </html>
Here is the sample output of the above reference example in PHP.