... Sooner or later, you may need to assign the contents of one zval container to another. ... To copy this complex kind of data, use the copy constructor . ... Now, in order to effectively duplicate its contents, the copy constructor is called. ... If you omit the call to the copy constructor in this example, both parameter and return_value would point to the same internal data, meaning that return_value would be an illegal additional reference to the same data structures. ...