What does :: mean in PHP?

Recommended manual:php complete self-study manual

In PHP, the double colon (::) operator is a range parsing operator. Also scoped operator. It is a static reference to a method in the class and can access static, const, and overridden properties and methods in the class.

When php calls internal static members of a class, or calls between classes, two colons (::) must be used.

Note: The "::" symbol can be considered similar to the "." in C language, and it is more like the :: class range operator in C (Perl).

Example:

class A{
  static $count = 0;
  static function haha(){
        //
  }  
  function diaoyoug(){
      self::haha();
        self::$count;
  }
}
a.b.c; /* C语言中的 */
a::b::c(); // C++ 中的函数
$a::b::c; # Perl 5中的标量

If the double colon (::) operator is used outside the class definition, it must be called using the class name. In PHP 5.3.0, you can use variables instead of class names.

Example: Using the double colon (::) operator outside the class definition

<?php
class Fruit {
    const CONST_VALUE = &#39;Fruit Color&#39;;
}
 
class Apple extends Fruit
{
    public static $color = &#39;Red&#39;;
 
    public static function doubleColon() {
        echo parent::CONST_VALUE . "\n";
        echo self::$color . "\n";
    }
}
 
Apple::doubleColon();
?>

Output:

Fruit Color Red

Related article recommendations:
1.Introduction to the meaning of the double colon::range parsing operator in php
2.The difference between the double colon range parsing operator and the arrow-> operator in php
Related video recommendations:
1.Dugu Jiujian (4)_PHP video tutorial
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