PHP class usage problem

How to use PHP classes: 1. Classes are defined through the class keyword; 2. When accessing objects, do not add [$] before the attribute name; 3. Access and modify members within the class through [->] Variable; 4. The return value of the function is returned through return.

php class usage method:

1. Syntax description

• Like other languages, classes are defined through the class keyword, and class names are in camel case. Define member variables. Add the modifiers public, private, and protected.

• Accessing and modifying member variables within a class through -> is the same as in most languages. Note: When accessing an object, do not add $ before the attribute name.

<?php
class Count 
{
    public function product ($num) {
 
        if ($n < 1 || $n >9) {
            return;
        }
        for ($i = 1; $i < $n; $i++) {
            for ($j = i; $j < $i; $j++) {
                
                    echo $j.&#39;x&#39;.$i.&#39;=&#39;.$j*$i.&#39;  &#39;;
                }
                echo &#39;<br>&#39;
 
            }
 
    }     
 
 
 
}
$math = new Count;
$math->product();
?>

3. Pointer reference method

$a = &$b;

$bChanges in the address space value pointed to will affect$a

4. The return value of the function is returned through return

<?php
class NewWorlk {
    public function isFlag() {
 
        return true;
    }
 
}
 
$nework = new NewWorlk();
$resualt = $nework->isFlag();
var_dump($resualt);
?>

5. Constructor and destructor

<?php
    public $host;
    public $user;
    public $pwd;
    public $dbName;
    public $post;
    public $charset;
//构造函数，两个下划线，对象初始化
    public function __construct($host, $user, $pwd, $dbName, $port, $charset) {
        $this->host = host;
        $this->user = user;
        $this->pwd = pwd;
        $this->$dbName = dbName;
        $this->post = port;
        $this->charset = charset;
    }
 
//析构函数,对象释放后会自动销毁所有变量并调用析构函数（先调用析构函数，后销毁对象本身）
    public function __destruct() {
        //一般都是断开数据库连接
     }
 
?>

6. Garbage collection mechanism

• In PHP, when an object has no reference pointing to it, it will become garbage. Object, PHP will enable the garbage collector to destroy the object.

• When the program exits, PHP will also enable the garbage collector and destroy objects.

• Explanation: The PHP garbage collection mechanism is only available after php5. The garbage collection mechanism used before php 5.3 is a simple "reference counting", that is, each memory object Allocate a counter. When the memory object is referenced by a variable, the counter is 1; when the variable reference is removed, the counter is -1; when the counter = 0, it indicates that the memory object is not used, the memory object is destroyed, and garbage collection is completed. Starting from php5.3, a new garbage collection mechanism is used. Based on reference counting, a complex algorithm is implemented to detect the existence of reference rings in memory objects to avoid memory leaks.

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