Double colon:: Usage in PHP, colon PHP usage _php tutorial

Source: Internet
Author: User
Tags access properties getcolor

Double colon:: Usage in PHP, colon php use case

A few days ago in Baidu know inside see someone asked PHP double colon:: The use, at that time to his answer is relatively concise because the phone typing is not convenient! It suddenly comes to mind today, so here's a summary of the double colons I've encountered:: What to use in PHP!

The double-colon operator, the scope-scoped operator, scope Resolution operator can access properties and methods overridden in static, const, and class.
Used outside of the class definition, called with the class name. In PHP 5.3.0, you can use variables instead of class names.

Program List: Accessing the class definition externally with a variable

<?phpclass Fruit {Const Const_value = ' Fruit Color ';} $classname = ' Fruit '; Echo $classname:: Const_value; As of PHP.. Echo fruit::const_value;? >program List: Used outside the class definition:: <?phpclass Fruit {Const Const_value = ' Fruit Color ';} Class Apple extends fruit{public static $color = ' Red ', public static function Doublecolon () {  echo Parent::const_val Ue. "\ n";  echo Self:: $color. "\ n"; }}apple::d Oublecolon ();? >

Program Run Result:

Fruit Color Red

Program List: Calling the parent method

<?phpclass fruit{protected function Showcolor () {  echo "fruit::showcolor () \ n";}} Class Apple extends fruit{//Override parent ' s definition public Function Showcolor () {  //But still call the parent function  Parent::showcolor ();  echo "Apple::showcolor () \ n"; }} $apple = new Apple (); $apple->showcolor ();? >

Program Run Result:

Fruit::showcolor ()
Apple::showcolor ()

Program List: Using scope qualifiers

<?php class Apple {public  function Showcolor ()  {   return $this->color;  }} class Banana {  public $color;  Public function __construct ()  {   $this->color = ' Banana is yellow ';  }  Public Function GetColor ()  {   return apple::showcolor ();  }} $banana = new Banana; Echo $banana GetColor ();? >

Program Run Result:

Banana is yellow

Program List: Methods for calling base classes

<?phpclass fruit{static function color () {  return ' color ';} static function Showcolor () {  echo "show". Self::color (); }}class Apple extends fruit{static function color () {  return ' red ';}} Apple::showcolor ();//output is "Show Color"!? >

Program Run Result:

Show Color

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