Simple example explanation of class constants in php

ClassConstant: In the class, data that remains unchanged during the running cycle is saved.

Definition:

const keyword

const constant name = constant value

Example:

class Student
{
       public  $stu_id;
       public  $stu_name;
       public  $stu_gender;
      
       const  GENDER_MALE = ‘男’;
       const  GENDER_FEMALE = ‘女’;
 
}

Class constants are not restricted by the access qualification modifier

Access:

Class::Constant name

Example:

class Student
{
       public  $stu_id;
       public  $stu_name;
       public  $stu_gender;
      
       const  GENDER_MALE = ‘男’;
       const  GENDER_FEMALE = ‘女’;
 
       public function construct($id,$name,$gender=’’)
       {
              $this->stu_id= $id;
              $this->stu_name= $name;
              $this->gender= ($gender == ‘ ’)?self::GENDER_MALE : $gender;
       }
 
}

Summary: The members that can be defined in a class are: constants, staticproperties, non-static properties, static methods, and non-static methods.

Note: $this represents the current object, does it always represent the object of the class where $this belongs?

No, because the value of $this does not depend on the class where $this is located, but depends on the execution object (execution environment) when the method where $this is located is called

The execution environment of the method. In which object the current method is executed,

$this in the method indicates which object.

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