{"id":105,"date":"2021-03-08T00:20:33","date_gmt":"2021-03-08T00:20:33","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=105"},"modified":"2021-07-12T09:20:15","modified_gmt":"2021-07-12T09:20:15","slug":"php-interface","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-oop\/php-interface\/","title":{"rendered":"PHP Interface"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about the PHP interface and how to use an interface to define a contract between classes.<\/p>\n\n\n\n

Introduction to the PHP interface #<\/a><\/h2>\n\n\n\n

An interface allows you to specify a contract that a class <\/a>must implement. To define an interface, you use the interface<\/code> keyword as follows:<\/p>\n\n\n

<?php<\/span>\n\ninterface<\/span> MyInterface<\/span>\n<\/span>{\n\t\/\/...<\/span>\n}\n<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
An interface consists of methods that contain no implementation. In other words, all methods of the interface are abstract methods. An interface can also include constants. For example:<\/p>\n\n\n
<?php<\/span>\n\ninterface<\/span> MyInterface<\/span>\n<\/span>{\n\tconst<\/span> CONSTANT_NAME = 1<\/span>;\n\n\tpublic<\/span> function<\/span> methodName<\/span>()<\/span><\/span>;\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Note that all the methods in the interface must be public.<\/p>\n\n\n\n
However, for interfaces, we say that a class implements an interface. <\/p>\n\n\n\n
A class can inherit from one class only. Howeer, it can implement multiple interfaces.<\/p>\n\n\n\n
To define a class that implements an interface, you use the implements<\/code> keyword as follows:<\/p>\n\n\n
<?php<\/span>\n\ninterface<\/span> MyInterface<\/span>\n<\/span>{\n\tconst<\/span> CONSTANT_NAME = 1<\/span>;\n\n\tpublic<\/span> function<\/span> methodName<\/span>()<\/span><\/span>;\n}\n\nclass<\/span> MyClass<\/span> implements<\/span> MyInterface<\/span>\n<\/span>{\n\tpublic<\/span> function<\/span> methodName<\/span>()<\/span>\n\t<\/span>{\n\t\t\/\/ ...<\/span>\n\t}\n}\n<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
When a class implements an interface, it’s called a concrete class<\/strong>. The concrete class needs to implement all the methods of the interface.<\/p>\n\n\n\n
interface<\/span> Readable<\/span>\n<\/span>{\n\tpublic<\/span> function<\/span> read<\/span>()<\/span><\/span>;\n}\n\ninterface<\/span> Document<\/span> extends<\/span> Readable<\/span>\n<\/span>{\n\tpublic<\/span> function<\/span> getContents<\/span>()<\/span><\/span>;\n}\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Why should you use PHP interfaces? #<\/a><\/h3>\n\n\n\n
The following are reasons for using interfaces:<\/p>\n\n\n\n
Like a class<\/a>, an interface can extend another interface using the extends<\/code> keyword. The following example shows how the Document<\/code> interface extends the Readable<\/code> interface:<\/p>\n\n\n
When you define a class (child class) that reuses properties and methods of another class (parent class), the child class extends the parent class<\/a>. <\/p>\n\n\n\n