Can a PHP class implement multiple interfaces?

Like most object-oriented programming languages, multiple inheritance is not supported in PHP. If you want to implement multiple inheritance functionality, you can use interfaces.

The idea of ​​an interface is:

Specify a series of functions that a class that implements the interface must implement. Generally, we use interface to declare an interface and declare some methods (i.e. functions) in the interface. Note that we only declare that we do not need to implement this function. Then, use class to declare a class and implements to use the interface, and then implement the methods declared in the interface in the class.

The general definition method is as follows:

Interface definition:

[修饰符] interface 接口名 [extends 父接口名列表]{
 
[public] [static] [final] 常量;
[public] [abstract] 方法;
}

Modifier: Optional , used to specify the access permission of the interface, the optional value is public. If omitted the default access permissions are used.

Interface name: Required parameter, used to specify the name of the interface. The interface name must be a legal Java identifier. Generally, capital letters are required.

extends Parent interface name list : Optional parameter, used to specify which parent interface the interface to be defined inherits from. When using the extends keyword, the parent interface name is a required parameter.

Method: The methods in the interface are only defined but not implemented.

Example:

接口定义：
public interface CalInterface   
{  
    final float PI=3.14159f;//定义用于表示圆周率的常量PI  
    float getArea(float r);//定义一个用于计算面积的方法getArea()  
    float getCircumference(float r);//定义一个用于计算周长的方法getCircumference()  
}
 
 
接口实现：
public class Cire implements CalInterface   
{  
    public float getArea(float r)   
    {  
        float area=PI*r*r;//计算圆面积并赋值给变量area  
        return area;//返回计算后的圆面积  
    }  
    public float getCircumference(float r)   
    {  
        float circumference=2*PI*r;      //计算圆周长并赋值给变量circumference  
        return circumference;           //返回计算后的圆周长  
    }  
    public static void main(String[] args)   
    {  
        Cire c = new Cire();  
        float f = c.getArea(2.0f);  
        System.out.println(Float.toString(f));  
    }  
}

Note that if the method specified in the interface is not implemented, a fatal error will be generated.

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