php - 公共，私有和受保护的有什么区别？(What is the difference between public, private, and protected?)

Question

When and why should I use public , private , and protected functions and variables inside a class?

(什么时候以及为什么应该在类内使用public ， private和protected函数和变量？)

What is the difference between them?

(它们之间有什么区别？)

Examples:

(例子：)

// Public
public $variable;
public function doSomething() {
  // ...
}

// Private
private $variable;
private function doSomething() {
  // ...
}

// Protected
protected $variable;
protected function doSomething() {
  // ...
}

  ask by Adam translate from so

Answer 1

You use:

(你用：)

• public scope to make that property/method available from anywhere, other classes and instances of the object.

  (public范围，以使该属性/方法可从任何位置，对象的其他类和实例使用。)

• private scope when you want your property/method to be visible in its own class only.

  (当您只希望您的属性/方法仅在其自己的类中可见时，请使用private范围。)

• protected scope when you want to make your property/method visible in all classes that extend current class including the parent class.

  (当您想使您的属性/方法在扩展当前类的所有类（包括父类）中可见时，请使用protected范围。)

More: (For comprehensive information)

(更多：（有关全面信息）)

• PHP Manual - Visibility

  (PHP手册-可见性)