static variables and functions
Static Variables
Member variables of a class can be made static by using the static keyword. Static member variables only exist once in a program regardless of how many class objects are defined! One way to think about it is that all objects of a class share the static variables. Consider the following program:
#include<iostream>
using namespace std;
class time1
{
public:
static int a;
};
// assigning value to static variable
int time1::a = 100;
// any random function
int myFunction()
{
// no need to pass it from any argument
// value will be preserved in functions
cout << time1::a << endl;
return time1::a;
}
int main()
{
// no need to call it from class objects
// because now this variable is free
// from object declarations to access it
cout << time1::a << endl;
time1::a = 200; // again accessing it
cout << time1::a << endl;
cout << "after function call" << myFunction();
getchar();
return 0;
}
Static functions
Non-static member functions can access all data members of the class: static and non-static. Static member functions can only operate on the static data members.
One way to think about this is that in C++ static data members and static member functions do not belong to any object, but to the entire class.
#include<iostream>
using namespace std;
class staticFunctions
{
public:
// static keyword with function definition
static void myFunction()
{
cout << "inside myFunction";
}
};
int main()
{
// no need to declare an object of the staticFunctions class
staticFunctions::myFunction();
getchar();
return 0;
}
