Why was the & symbol needed in PHP 4 for object instantiation?

In PHP 4, the & symbol was needed for object instantiation because objects were passed by reference by default. This means that without the & symbol, a new object would be created as a copy of the original object, rather than as a reference to it. To avoid this behavior and ensure that objects are passed by reference, the & symbol was required when instantiating objects in PHP 4.

// PHP 4 object instantiation using the & symbol
$object = &new ClassName();