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Static Data Member And Static Member Function

Example of static data member​

  • Static data members of a class are attributes the class.
  • The memory for static data members is common to each object.
#include <iostream>
using namespace std;

class Base {
public:
  int x;
  static int y; // declaration
};

int Base::y; // definition

int main() {
  Base b1, b2;
  b1.x = 10;
  b1.y = 30;  // Base::y
  b2.x = 20;
  Base::y = 40;

  cout << b1.x << " " << b2.x << endl;
  cout << b1.y << " " << b2.y << endl;
}

output

10 20
40 40

Example of static member function​

  • Static member functions can only access static data members.
  • Non-static member functions can access static or non-static data memebers
#include <iostream>
using namespace std;

class Base {
public:
  int x;
  static int y; // declaration
  void printXY() {cout << x << " " << y << endl;}
  static void printY() {cout << y << endl;}
};

int Base::y; // definition

int main() {
  Base b1, b2;
  b1.x = 10;
  b1.y = 30;  // Base::y
  b2.x = 20;
  Base::y = 40;

  b1.printXY();
  b1.printY();  // Base::printY()

  b2.printXY();
  Base::printY();

  return 0;
}

output

10 40
40
20 40
40

From​

Static Data Member And Static Member Function In C++ - Youtube