Static members of a C++ class

Static members of a C++ class

We can define class members static using static keyword. When we declare a member of a class as static it means no matter how many objects of the class are created, there is only one copy of the static member.

A static member is shared by all objects of the class. All static data is initialized to zero when the first object is created, if no other initialization is present. We can't put it in the class definition but it can be initialized outside the class as done in the following example by re-declaring the static variable, using the scope resolution operator :: to identify which class it belongs to.

Let us try the following example to understand the concept of static data members:

~IntArray()

{

#include<iostream>

usingnamespacestd;

classBox

{

public: staticintobjectCount;

// Constructor definition

Box(double l=2.0,double b=2.0,double h=2.0)

{

cout<<"Constructor called."<<endl; length= l;

breadth= b;

height= h;

//  Increase every time object is created

objectCount++;

}

doubleVolume()

{

return length * breadth * height;

}

private:

double length;// Length of a box

double breadth;// Breadth of a box

double height;// Height of a box

};

//  Initialize static member of class Box

intBox::objectCount=0;

int main(void)

{

BoxBox1(3.3,1.2,1.5);// Declare box1

BoxBox2(8.5,6.0,2.0);// Declare box2

//  Print total number of objects.

cout<<"Total objects: "<<Box::objectCount<<endl;

return0;

}

When the above code is compiled and executed, it produces the following result:

Constructor called.

Constructor called.

Total objects:2