OOP is all about creating modular code, so our object oriented PHP code will be Classes are the blueprints for php objects - more on that later. One of the big. Let us consider the example of a User object; a user will have a name, an age, objects and classes were introduced into PHP 3 in In , PHP 4 was. 10 items Chapter Advanced Object-Oriented Programming Concepts. The code takes full advantage of the capabilities of PHP 5 but, where possible.
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Object Oriented Programming in PHP - A simple and short PHP tutorial and complete You define a class once and then make many objects that belong to it . PHP Advanced and Object-Oriented Programming new HTML5 design for the example chapter. And for doing so .. uses objects instead of procedural code. Recognizing the Differences Between Objects and Classes A class. is like a blueprint for a house An object. then. for example. is like the actual house Classes.
Here child class will inherit all or few member functions and variables of a parent class. This is also called a base class or super class. This is also called a subclass or derived class. For example function name will remain same but it take different number of arguments and can do different task.
Similarly functions can also be overloaded with different implementation. A set of braces enclosing any number of variable declarations and function definitions.
Function definitions look much like standalone PHP functions but are local to the class and will be used to set and access object data. Creating Objects in PHP Once you defined your class, then you can create as many objects as you like of that class type.
Following is an example of how to create object using new operator. Next we will see how to access member function and process member variables. Calling Member Functions After creating your objects, you will be able to call member functions related to that object. One member function will be able to process member variable of related object only. Following example shows how to set title and prices for the three books by calling member functions.
So we take full advantage of this behaviour, by initializing many things through constructor functions. You can pass as many as arguments you like into the constructor function. Following example will create one constructor for Books class and it will initialize price and title for the book at the time of object creation. We can initialize these two member variables at the time of object creation only.
You can release all the resources with-in a destructor. Inheritance PHP class definitions can optionally inherit from a parent class definition by using the extends clause. Automatically has all the same member functions as the parent, which by default will work the same way as those functions do in the parent.
Following example inherit Books class and adds more functionality based on the requirement. Function Overriding Function definitions in child classes override definitions with the same name in parent classes. In a child class, we can modify the definition of a function inherited from parent class.
In the following example getPrice and getTitle functions are overridden to return some values. If you wish to limit the accessibility of the members of a class then you define class members as private or protected.
But in reality, there is a lot of code that runs in the background. Therefore, abstraction helps to reduce complexity. Now what does the abstract keyword mean?
If a class is declared abstract, it cannot be instantiated, which means you cannot create an object of an abstract class. Also, an abstract class can contain abstract as well as concrete methods.
In an interface, each method is public and abstract but it does not contain any constructor.
So an interface basically is a group of related methods with empty bodies. But their working is going to be different. Therefore, not all my subclasses have the same logic written for change gear.
But suppose, someone else is driving a super car, where it increment by 30kms or 50kms. Again the logic varies. Similarly for applybrakes, where one person may have powerful brakes, other may not. After that, I will create a child class which implements this interface, where the definition to all these method varies. SpeedUp ; A6.
Implementing an interface allows a class to become more formal about the behavior it promises to provide. So I hope you guys are clear with the interface and how you can achieve abstraction using it.
Finally, the last Object oriented programming concept is Polymorphism. It is the ability of a variable, function or object to take on multiple forms. In other words, polymorphism allows you define one interface or method and have multiple implementations. Fast bowlers, Medium pace bowlers and spinners.
As you can see in the above figure, there is a parent class- BowlerClass and it has three child classes: FastPacer, MediumPacer and Spinner. Bowler class has bowlingMethod where all the child classes are inheriting this method. As we all know that a fast bowler will going to bowl differently as compared to medium pacer and spinner in terms of bowling speed, long run up and way of bowling, etc. And same happens with spinner class. The point of above discussion is simply that a same name tends to multiple forms.
All the three classes above inherited the bowlingMethod but their implementation is totally different from one another.
In this, a reference variable is used to call an overridden method of a superclass at run time. Method overriding is an example of run time polymorphism. Method overloading is an example of compile time polymorphism. Method Overloading is a feature that allows a class to have two or more methods having the same name but the arguments passed to the methods are different.
Unlike method overriding, arguments can differ in: Number of parameters passed to a method Datatype of parameters Sequence of datatypes when passed to a method. Do read my next blog on Java String where I will be explaining all about Strings and its various methods and interfaces.