PHP object-oriented classes and instantiated objects

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Class

Declaration

[修饰符] class 类名
{
    [属性]
    [方法]
}

Notes:

1) The class name follows the camel case naming convention that starts with uppercase

2) The opening and closing tags of curly braces must be on a line of their own.

Modifier

private     私有

protected   保护

public      公共    

var         被视为public  (不建议使用)

Access permission

Instantiation

Use the new keyword to instantiate.

Brackets are not required.

Example

// 1.声明类
class Dog
{
    // 2.定义属性
    public $name = '旺财';
    public $sex = null;


    // 3.定义方法
    public function bark()
    {
        echo '汪汪~';
    }
}

// 4.实例化
$d1 = new Dog();

Instantiated object

Invocation of properties and methods

Use

-> , to access non-static properties | methods.

Example

// 声明类
class Dog
{
    // 定义属性
    public $name = '旺财';
    public $sex = null;


    // 定义方法
    public function bark()
    {
        echo '汪汪~';
    }
}

// 实例化
$d1 = new Dog();

// 使用属性和方法
echo $d1 -> name;
echo &#39;<br/>&#39;;
echo $d1 -> bark();

Internal call

When a method is called inside a class definition, you can use pseudo variables

$this .

$this represents the object being used.

Example:

// 声明类
class Dog
{
    // 定义属性
    public $name = '旺财';
    public $sex = null;

    public function intruduce()
    {
        echo '我的名字是'.$this->name;
    }
}

Transfer assignment

1)

Simple type, both sides of the assignment, mutually independent.

2) When

composite type, the identifier of the object is stored in the transfer assignment, so the changes are consistent .

Simple type example:

$a = 'abc';

// 传递赋值
$b = $a;

// 更改a的值
$a = 'qq';

var_dump($a);   // qq
var_dump($b);   // abc

Composite type example:

class MyClass
{
    public $str = 'abc';
}

// $a 存的是对象的标识符
$a = new MyClass();

// 传递赋值  相当于把标识符赋值给了$b
$b = $a;

var_dump($a);    // abc
var_dump($b);    // abc

// 更改a对象str属性的值
$a -> str ='111';

// $a和$b存的都是标识符
var_dump($a);    // 111
var_dump($b);    // 111


// 更改a本身的值
$a = 123;

var_dump($a);    // 123
var_dump($b);    // 111   对象标识符

Reference assignment

Whether it is Whether it is a simple type or a conforming type, both changes are consistent.

Example:

$a = 'abc';

// 引用赋值
$c = &$a;

var_dump($a);   // qq
var_dump($c);   // qq

Related recommendations:

php basic object-oriented concepts

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