PHP | PHP5 – Being Static

Class properties

This is another name for properties (or methods) declared static inside classes as these properties belong to a class and not to any instance/object.

The keyword ‘static’ is used to define static properties.

Sample program:
class ClassA{
static $variableA;
static $variableB = 10;
}

To print the value of variableB, you will use

echo “Variable B in ClassA = ” . ClassA::$variableB;

To further expand on this topic,

Print static variables value from within the class
class ClassA{
static $variableA;
static $variableB = 10;

function __construct(){
echo “To print variableB inside class “. self::$variableB;
}
}

As static properties or methods are not tied to an object, we can call them without instantiating a class. Depending on the place from where the call to the static member is made, we use the identifier “self” or the name of the class with “::” or not “$this”.

class classB{

static $classVarA = 5;

static function memberA(){
echo “value of classVarA “. self::$classVarA;
}

}

To display the variable of classVarA from outside the class, you can call the static method by

classB::memberA();

If you have another class “classC” inheriting “classB”, then you can access the property/method in ClassB using “parent::” identifier as below

classC extends classB{

function __construct(){
echo “Variable from B ” . parent::$classVarA;
}

}