Static data members and functions in c++

Hello friends, in this post today, we learn Static data members and functions in c++. so lets start...

Static data members and functions 

Static Data Members:-

We know that whenever an object is created separate copies of data members are created for each object. 

Data members of the class which are shared by all objects are known as static data members also known as (class variables).

But in case of static data members only one copy of static data members is available which is shared among all the objects created.

They are created by placing static keyword before variable declaration.

Static members are declared inside the class but are initialized outside the class as :

data_type class_name : : static_variable =value;

It is initialized to zero when value is not given by the programmer. 

It is visible only within the class but its lifetime of a static variable is the entire program.

Static members are generally used to maintain values common to the entire class.

Example:-

#include<iostream>

using namespace std;

class static_variable

{

   private:

   static int s; //static variable

int i;

   public:

   void input(int x)

   {

     i=x;

   }

   void show()

   {

    cout<<"i="<<i<<endl;

    cout<<"s="<<s<<endl;

   }

};

int static_variable::s=20; // assigning static variable value

int main()

{

static_variable d1,d2;

d1.input(10);

d1.show();

d2.input(34);

d2.show();

return 0;

}

Output:-

i=10

s=20

i=34

s=20

Static member functions:

Static functions are functions which are made static by placing keyword static before function definition in side the class.

All static function of class must be defined inside the class. You cannot separate the declaration and definition of a static member function.

In a static function only static data members, other static variables or other static function can be used.

Though static member function is called using class name with : : operator. It can be called explicitly using objects of the class.

Static member functions are associated with a class, not with any object.

They cannot be virtual.

They cannot be declared as constant or volatile.

A static member function can be called, even when a class is not instantiated.

There cannot be static and non-static version of the same function.

A static member function does not have this pointer.

Example:

#include <iostream>

using namespace std;

class static_Demo

{

  public:

  static void show()   //static function 

  {

    cout<<"Demo of static function \n";

  }

};

int main()

{

 static_Demo d1;

 static_Demo::show();  // accessed using scope resolution operator

 d1.show();            // accessed using object

 return 0;

}

Output:-

Demo of static function 

Demo of static function 

I hope that whatever information I have given in this post today, you have liked it and you have understood it.so keep learning and wait for the next post that will help you to increase your knowledge with the something new information.

Thank you so much for reading. And take care about yourself and your family.