Static

Static Variables

Scope: Limited to the block/function where it’s declared
Lifetime: Entire program (exists from start to end)
Value persists across function calls

Use cases:
- Counting function calls
- Caching values
- Maintaining state without global variables

void fun()
{
    static int v = 0;
    int a = 10;
    v++;
    cout << a << " " << v;
}

int main()
{
    fun(); // 10 1
    fun(); // 10 2
    fun(); // 10 3
}

Static Data Members

class Student {
public:
    static int totalStudents;   // Declaration
};

int Student::totalStudents = 0; // Definition

Only one copy exists for the entire class
Shared by all objects
Not tied to any specific instance, can be accessed directly using class name.

Lifetime: Exists for the entire program (Created once, destroyed at program end)

Static Member Functions

Static members functions are functions of a class, they can be called using class name, without creating object of a class.

They can access only static data members of a class, they cannot access non-static members of a class.

class Math {
public:
    static int add(int a, int b) {
        return a + b;
    }
};

Belong to the class, not to objects (Hence, No this pointer)
Can be called without creating an object
Cannot access non-static members
Can only access:
- Static data members
- Other static functions

Static Example

class Test
{
private:
    int a;
    static int count;

public:
    Test() {
        a = 10;
        count++;
    }

    static int getCount() {
        return count;
    }
};

int Test::count = 0;

int main()
{
    Test t1, t2;
    
    cout << Test::getCount();   // 2
    
    cout << t1.getCount();      // 2
    // No harm in calling it using a object
}

Last modified: 08 February 2026