Static Members

Static functions and properties are declared in the class body but don't need created instances for their usage.

Static Properties

Static properties store value about the class. The value is specific for the class.

Static properties are declared via the keyword static.

The syntax for declaring static member:

static memberType memberName;

The syntax for setting value to static member is:

ClassName::memberName = value;

Here's an example:

#include <iostream> #include <string> using namespace std; class Car { private: string model; public: Car(string modelValue) { cout << "Object created." << endl; model = modelValue; // Increment static member: carsCount++; } static int carsCount; }; // Set value to static member: int Car::carsCount = 0; void main() { cout << "Initial Cars Count: " << Car::carsCount << endl; // create instances: Car carobj1("Toyota Corolla"); Car carobj2("Peugeot 508"); Car carobj3("Renault Clio"); cout << "Final Cars Count: " << Car::carsCount; }

Output:

Initial Cars Count: 0 Object created. Object created. Object created. Final Cars Count: 3

Couple of things to notice:

• When an object is created via the parametrized constructor (lines 12 - 20), then the static member value is incremented (due to line 19).
• At line 26 a value is set to the static member. It happens before the the main function lines 28 - 40 executes.
• When the static member is printed for the first time (line 31), it's value is 0.
• After objects were created via the parametrized constructor, it's value has reached 3 - the count of the created objects.

Static Functions

Static functions cannot use non-static class member though declared in class.

They are defined via the keyword static.

Syntax for defining:

static funcType funcName(args) { // code }

Syntax for calling:

ClassName::funcName(args);

Here's an example:

#include <iostream> #include <string> using namespace std; class Person { private: string name; public: static void printHi() { cout << "Hello!"; } }; void main() { Person::printHi(); }

Output:

Hello!