PHP passes copies of the information to and from the function; this is known as passing and returning by value.
Sometimes you may want your function to work on the original information, rather than on a copy.
You can use PHP references to work with the reference of variable.
A reference is like an alias to the variable.
When you create a reference to a PHP variable, you have two ways to read or change the variable's contents:
Here's a simple example that creates a reference to a variable:
<?php $myVar = 123;/*from ww w. j av a 2s. c o m*/ $myRef = &$myVar; $myRef++; echo $myRef."\n"; // Displays"124" echo $myVar."\n"; // Displays"124" ?>
First a new variable, $myVar, is initialized with the value 123.
Next, a reference to $myVar is created, and the reference is stored in the variable $myRef.
The ampersand (&) symbol after the equals sign; using this symbol creates the reference.
The next line of code adds one to the value of $myRef.
Because $myRef actually points to the same data as $myVar, both $myRef and $myVar now contain the value 124.