Questions about changing the variable value of the php reference address

$foo = 'Bob'; // Assign 'Bob' to $foo
$bar = &$foo; // Reference $foo through $bar
echo $foo.'< ;br/>';
$bar = "My name is $bar"; // Modify the $bar variable
echo $bar.'';
echo $foo.'?>

output: Bob My name is Bob My name is Bob

You can see that the original value is modified, which occurs after the reference and assignment, but the original variable will not change before it is assigned. Articles you may be interested in: Detailed introduction to php reference passing by value Understand the difference between passing by value and passing by reference in PHP through examples Look at the efficiency issues of php address reference through examples Quotes in PHP, "&" explanation