<?php
$foo = 'Bob';              // Assign the value 'Bob' to $foo
$bar = &$foo;              // Reference $foo via $bar.
$bar = "My name is $bar";  // Alter $bar...
echo $foo;                 // $foo is altered too.
echo $bar;
?>

Why do '$bar = "My name is $bar";'? And then do 'echo $foo' *before* you 'echo $bar'? The point you're trying to make is surely expressed  better like this:

<?php
$foo = 'Bob';              // Assign the value 'Bob' to $foo
$bar = &$foo;              // Reference $foo via $bar.
$bar = "Dave";  // Alter $bar...
echo $bar;                
echo $foo; // $foo is altered too.
?>


Clearer for the newcomer to programming, ne?