1. Lab – 2018/04/12
implement getTotalCount to return how many ‘nMatrix’s are allocated(exist)
(modify constructor and destructor, use static variable and static function)
int main() {
nMatrix a(5, 3);
cout <<nMatrix::getTotalCount(); << endl; // print 1
nMatrix b(5, 1);
nMatrix c(3, 5);
cout << nMatrix::getTotalCount(); << endl; // print 3 }

2. Hint 1 – static variables
void demo() { // static variable static int count = 0; cout << count << " "; // value is updated and // will be carried to next // function calls count++; ]
int main() {
for (int i=0; i<5; i++)
demo();
return 0; }

3. Hint 2 – static variables in a class
class GfG { public: static int i; GfG() // Do nothing };
int main() {
GfG obj1;
GfG obj2;
obj1.i = 2;
GfG::i = 3;
// prints value of i
cout << obj1.i<<" "<<obj2.i << endl;
cout << GfG::i << endl; }

4. Hint 3 – static functions in a class
class GfG { public: // static member function static void printMsg() cout<<"Welcome to GfG!"; } };
int main() {
// invoking a static member function
GfG::printMsg(); }