The difference between PHP abstract and interface

1.php Interface class: interface

In fact, their role is very simple. When many people develop a project together, they may all call some classes written by others. Then you will ask, how can I You know how the implementation method of a certain function is named. At this time, the PHP interface class comes into play. When we define an interface class, the methods in it must be implemented by the following subclasses, such as:
1 interface Shop
2 {
3 public function buy($gid);
4 public function sell($gid);
5 public function view($gid);
6}

I declare a shop interface class and define three methods: buy, sell, and view. Then all subclasses that inherit this class must implement these three methods. None of them will work, and if the subclass doesn't implement these, it won't 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 matter how you do it, I don’t care how you do it. That’s up to you. things, such as:
class BaseShop implements Shop
{
public function buy($gid)
{
echo(‘You purchased the product with ID:’.$gid.’);
}
public function sell($gid)
{
echo(‘You sold the product with the ID:’.$gid.’);
}
public function view($gid)
{
echo(‘You viewed the product with the ID:’.$gid.’);
}
}

Think about it, in a large project where many people collaborate, it is very convenient to have an interface class, so that you don’t have to ask others what the method name of your certain function is. Of course, if I can't help you if you like this.

Conclusion: The interface class is the leader of a class, pointing out the direction, and the subclass must complete its specified method.

2.php Abstract class: abstract

In fact, abstract classes and interface classes are partly similar. I remember where I saw such a sentence, abstract class extracts the similar part. This sentence looks very similar. Funny, in fact, it tells the truth about abstract classes. The function of abstract classes is that when you find that many of your classes use many methods that you are constantly writing repeatedly, then you can consider using abstract classes. You may say "Isn't it possible for me to rewrite a class? For each public class, I instantiate this public class and call the same method." It is possible here. In fact, this is what abstract classes do, but they omit it. This step of instantiation makes it as convenient as calling the method of this class directly, and you can also overload this method. Such as:
1 abstract class BaseShop
2 {
3 public function buy($gid)
4 {
5 echo(‘You purchased the product with the ID:’.$gid.’);
6 }
7 public function sell($gid)
8 {
9 echo(‘You sold the product with the ID:’.$gid.’);
10 }
11 public function view($gid)
12 {
13 echo(‘You viewed the product with the ID:’.$gid.’);
14 }
15}
16 class BallShop extends BaseShop
17 {
18 var $itme_id = null;
19 public function __construct()
20 {
21 $this->itme_id = 2314;
22 }
23 public function open()
24 {
25 $this->sell($this->itme_id);
26 }
27}
28

Here is an example. Like the above, I defined a store class, extracted all its similar parts, buy, sell, and view, and implemented them in the abstract class. These methods, then the subclass that inherits it will automatically obtain these methods, and the subclass will do its own unique things, introduce duplication of code, and improve reusability.

Conclusion: An abstract class is a service provider of a class. It has many services. You don’t have to use them. You can use them when needed. If you feel dissatisfied without providing services, you can also do it yourself. The abstract function method is somewhat similar to the interface. It is a method declared in the parent class and must be implemented in the subclass. However, methods not declared with abstract will become public methods of the subclass. There is no need to implement them in the subclass