In-depth understanding of PHP class and constructor analysis

Everyone has a certain understanding of classes. Here we only introduce the noteworthy aspects of classes in php

----Creation of classes----

php Use the keyword class to create a class, and use a pair of braces
such as:

class name{
  public $n="";
  private $u="";

  public function name() {
    $n="233";
    $u="23333";
  }

  public function rename($newn){
     $this->n=$newn;//this表示这个类
  }
}

without a semicolon at the end. Then $n,$u is a field; name() is a constructor (construct() can also define a constructor, see below for details), which can assign values ​​to fields; rename() is a method.

----Field----

Comparison
$obj=new name();
echo $obj->n;
with
$obj=new name();
echo $obj-> ;u;

The former is executable, but the latter is not possible because private is declared before $u. This is similar to c++.

Code:

public static $nm ="2333333333333333" ;

Declares a static field for the function.
The variable can be accessed directly through the class name and ::

echo name::$nm;

This is also similar to c++.

You can also access static fields in the class through self::+$+variable name . At this time, self is equivalent to $this-> ;.

The use of methods is similar to fields

##----Constructor----

class name{
  public $n="";
  private $u="";

  public function construct() {
    $n="233";
    $u="23333";
  }

  public function rename($newn){
     $this->n=$newn;
  }
}

construct($name="",$sex="man",$age=0) {}
When declaring an object

$obj= new name("我","man",28);

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