What is static member function? & what is the advantages of it's use in c++ program.

Question

Why we use static member function in program. What is the main advantages of it's over non-static member function.

Answer 1

Static member functions become useful when you want the class as a whole to have a function, instead of each individual object. With a static member function, you can then change static variable data. For example, a class of cars might have a total count of how many cars you have created:

static int nCars;

Then you can up the count each time a car is created (in the car constructor) with a static member function:

static void CountCars() { Car::nCars++; }
*******************************************************

#include <iostream>
using namespace std;

class Car {
public:
static int nCars;
static void CountCars();
Car() { CountCars(); }

};

int Car::nCars = 0;
void Car::CountCars() { Car::nCars++; } // you MUST define statics OUTSIDE of the class

int main() {
Car firstCar;
cout << Car::nCars << endl; // outputs 1
Car secondCar;
cout << Car::nCars << endl; // outputs 2

return 0;
}

Answer 2

Use the search function.

Answer 3

Static function:
+ : it could be called without existing real object
- : it doesn't have pointer to real object ("this")
For example, "singleton class" (with private constructor) is great example of static function advantage using.