Count the number of objects using Static member function

• 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.
• A static member function can only access static data member, other static member functions and any other functions from outside the class.
• By declaring a function member as static, we make it independent of any particular object of the class. A static member function can be called even if no objects of the class exist and the static functions are accessed using only the class name and the scope resolution operator :: .
• 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.

Input : Here  we are not asking for input from the user
Output :count:2
count:3
object number :1
object number :2
object number :3

Input :Here we are not asking for input from the user
Output :count:2
count:3
object number :1
object number :2
object number :3

// C++ program to Count the number of objects
// using the Static member function
#include <iostream>
using namespace std;
class test {
    int objNo;
    static int objCnt;

public:
    test()
    {
    objNo = ++objCnt;
    }
    ~test()
    {
    --objCnt;
    }
    void printObjNumber(void)
    {
        cout << "object number :" << objNo << "\n";
    }
    static void printObjCount(void)
    {
        cout << "count:" << objCnt<< "\n";
    }
};
int test::objCnt;
int main()
{
    test t1, t2;
    test::printObjCount();

    test t3;
    test::printObjCount();

    t1.printObjNumber(); 
    t2.printObjNumber(); 
    t3.printObjNumber();
    return 0;
}

count:2
count:3
object number :1
object number :2
object number :3