class my_class
{
function my_funct ($my_param)
{
user_error ("Please define me", E_ERROR);
}
function b()
{
return 10;
}
}

A. Multiple inheritance
B. Interfaces
C. Abstract methods
D. Private methods
E. Function overloading

Answer:
Abstract methods

A. Model-view-controller
B. Abstract factory
C. Singleton
D. Proxy
E. State

Answer:
Singleton

class my_class
{
var $my_value = array();
function my_class ($value)
{
$this->my_value[] = $value;
}
function set_value ($value)
{
$this->$my_value = $value;
}
}
$a = new my_class ('a');
$a->my_value[] = 'b';
$a->set_value ('c');
$a->my_class('d');

• c
• b
• a
• d
• e

Answers:
b,a and d

The set_value method of my_class will not work correctly because it uses the expression $this->$my_value, which is a “variable variable” that, under the circumstances will never correspond to any real property of the class.