Meaning :: Operator in C # and PhP

in class-based object oriented programming languages ​​(e.g. C ++, Java, PHP, ...) there are properties (also called fields) that are data and are just variables or constants, and methods that are the functionality of a class and are actually functions (routines). each class can be created as an object. each object has all the data and functionality of the base class at the beginning, but the data can change and differ from one object to another. there are 2 kinds of properties and 2 kinds of methods. some properties are shared among all objects of the class. this means that if you change this class data, then the same data of all objects that were created will be changed to the new value. such properties are called class properties or static properties (because,when you define these variables, in most languages ​​you will use the static keyword). some other properties are specific to each object. changing the data of an object does not affect the data of other objects. they are called object properties or instance properties. some methods are called from an object are called object methods. these are object methods and their use, you need to create a class first and use an object. some other methods are called using the class itself. these are class methods (or static methods), if you want one of these functions, there is no need for an object. to use properties / methods of an object, in PHP (like C ++) you have to use the → operator:some other properties are specific to each object. changing the data of an object does not affect the data of other objects. they are called object properties or instance properties. some methods are called from an object are called object methods. these are object methods and their use, you need to create a class first and use an object. some other methods are called using the class itself. these are class methods (or static methods), if you want one of these functions, there is no need for an object. to use properties / methods of an object, in PHP (like C ++) you have to use the → operator:some other properties are specific to each object. changing the data of an object does not affect the data of other objects. they are called object properties or instance properties. some methods are called from an object are called object methods. these are object methods and their use, you need to create a class first and use an object. some other methods are called using the class itself. these are class methods (or static methods), if you want one of these functions, there is no need for an object. to use properties / methods of an object, in PHP (like C ++) you have to use the → operator:these are object methods and their use, you need to create a class first and use an object. some other methods are called using the class itself. these are class methods (or static methods), if you want one of these functions, there is no need for an object. to use properties / methods of an object, in PHP (like C ++) you have to use the → operator:these are object methods and their use, you need to create a class first and use an object. some other methods are called using the class itself. these are class methods (or static methods), if you want one of these functions, there is no need for an object. to use properties / methods of an object, in PHP (like C ++) you have to use the → operator:

object->method();
object->property;

      

        
        
        
      

    

to use properties / methods of a class in PHP (like C ++) you have to use the operator:

class::method();
class::property;

      

        
        
        
      

    

in languages ​​like Jave, operator. used for all properties / methods:

object.method();
class.property;

      

        
        
        
      

    

suppose you have a Circle class. this class defines some data, such as radius and center coordinates, and a constant for the PI value. also has a method for calculating the area of ​​a circle.

here is some PHP code to make it clear:

<?php
class Circle {
    public $radius;
    public $centerX;
    public $centerY;
    public static $PI = 3.1415;
    public function __construct($r,$x,$y) {
        $this->radius = $r;
        $this->centerX = $x;
        $this->centerY = $y;
    }
    public function getArea() {
        return self::$PI * $this->radius * $this->radius;
    }
}
$circle1 = new Circle(10,0,0);
echo $circle1->getArea() . "<br>\n";
$circle2 = new Circle(15,10,12);
echo $circle2->getArea() . "<br>\n";
Circle::$PI = 3.14;
echo $circle1->getArea() . "<br>\n";
echo $circle2->getArea() . "<br>\n";
?>

      

        
        
        
      

    

in this example, we define an environment class that has object properties (radius, centerX, CenterY), object methods (getArea ()), and a class property (PI). by changing the static PI property, the scope of both objects will be affected.

Consider the following example:

namespace  A { 
    public class MyClass { }
} 

namespace namespaceB
{
    public class A
    {
        public class MyClass { }
    }

    public class OtherClass
    {
        public A.MyClass MyAClass;
    }
}

      

        
        
        
      

    

Explanation:

In the above example, the compiler always resolves MyAClass for the .BAMyClass type namespace.

If you want it to be A.MyClass, there was no way to do this before C # 2.0.

In C # 2.0, you have to use: public class MyOtherClass

{ public global::A.MyClass yAClass; }

      

        
        
        
      

    

To indicate that you should not use the local namespace scope, but rather the root namespace.

In C #, the global :: operator is used to check that the next name is interpreted as a global name expression instead of a local one. The main use for this is when developers have a nested namespace where the name is the same as the global namespace. Without global :: operator, there is no access to the global version.

namespace Foo { 
  namespace System {
    class DateTime {} 
    class Example {
      object Example() { 
        return System.DateTime.Now; // Returns Foo.System.DateTime.Now
        return global::System.DateTime.Now; // Returns mscorlib,System.DateTime.Now
      }
    }
  }
}

      

        
        
        
      

    

In PHP it is called the Scope Resolution Operator (Paamayim Nekudotayim) and allows access to members or constants within a class