what is php interface

Characteristics of PHP interface

1. The methods of the interface must be public.

2. Interface methods are abstract by default, so do not add abstract in front of the method name. (Recommended learning: PHP Programming from entry to proficiency)

3. Interfaces can define constants, but cannot define member attributes. The definition and usage of constants are the same as those in classes.

4. A class can implement multiple interfaces (equivalent to integrating multiple functions into one, such as a mobile phone that implements the functions of PHS, MP3, and MP4)

5. Interfaces can also be inherited interface.

PHP, like most object-oriented languages, does not support multiple inheritance. If you need to implement the multiple inheritance function, in PHP, you can use interfaces. It is PHP's way to solve the problem of multiple inheritance. After version php5.4, there is a new feature trait of classes. If you are interested, you can download it on Baidu.

The idea of ​​an interface is to specify a series of functions that a class that implements the interface must implement. If the method specified in the interface is not implemented, a fatal error will be generated.

When many people develop a project together, they may all call some classes written by others. Then you may ask, how do I know how the implementation method of a certain function is named? Well, at this time the PHP interface class interface comes into play. When we define an interface class, the methods in it must be implemented by the following subclasses, for example:

Interface interface is a regulation, What is used for inheritance is a bit like the method defined in an abstract class, but it is not instantiated, but requires other classes to

implement it, and all the interface definitions must be implemented one by one. method.

interface Shop
{
public function buy($gid);
public function sell($gid);
public function view($gid);
}

I declare a shop interface class and define three methods: buy, sell, and view. Then all subclasses that inherit this class must implement this None of the three methods will work. If the subclass does not implement these, it will not work.

In fact, the interface class is, to put it bluntly, the template of a class and the regulations of a class. If you belong to this category, you must follow my regulations. No one less will work, but how do you do it specifically? I don’t care, that’s your business, like:

class BaseShop implements Shop
{
public function buy($gid)
{
echo('你购买了ID为 :'.$gid.'的商品');
}
public function sell($gid)
{
echo('你卖了ID为 :'.$gid.'的商品');
}
public function view($gid)
{
echo('你查看了ID为 :'.$gid.'的商品');
}
}

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