"PHP" Object-oriented (iv)

Knowledge Point: AI
One, A and abstract (abstraction Class)
A) modifiers for abstract classes, decorated classes, and Member methods
b) Note: The modified class cannot be instantiated, and the modified method cannot have a program body
c) If a class is decorated with an abstract, it means that he has an incomplete member method, two solutions, either we implement the unfinished method in this class, or we let the subclass inherit him and complete the unfinished function before it can be instantiated!
II, I = Interface (interface)
A) interface declares an interface class
b) interface can contain only constant definitions, and Member methods
c) Note: The Member method cannot have a program body inside the interface class
d) Interface interface class We can only use implements to implement, but not to use extends inheritance
e) Using interface declaration of the interface class, not a function is implemented, can only let subclasses use implements to implement all of its functions or part of the function, if the subclass is only part of the function, subclass or an abstract class, at this time, only let grandson class to implement all the functions, The interface class is now implemented!
Three main characteristics of object-oriented:
A) package
b) Inheritance
c) polymorphic
I. Allowing a class to do many aspects of work

"PHP" Object-oriented (iv)