Implement a Program to Demonstrate Static Data Members and Static Functions in C++

In C++, the `static` keyword can be applied to both data members and member functions within a class. These static members are shared by all objects of the class, rather than each object having its own copy. This concept is extremely useful when you want a common value or behavior across all instances of a class.

In this blog, we’ll learn:

• What static data members are
• What static member functions are
• How to implement and use them in a C++ program

🔹 What are Static Data Members?

A static data member of a class is shared among all objects of the class. Unlike normal (non-static) data members, which are unique to each object, static members are allocated only once in memory and retain their value across objects.

🔹 What are Static Member Functions?
A static member function can access only static data members or other static functions. It is invoked using the class name rather than an object of the class.

✅ C++ Program: Demonstrate Static Data Members and Static Functions
#include <iostream>
using namespace std;
class Student {
private:
    int rollNo;
    string name;
    static int studentCount; // Static data member
public:
    // Constructor
    Student(string n, int r) {
        name = n;
        rollNo = r;
        studentCount++; // Increment count when object is created
    }
    // Display student details
    void display() {
        cout << "Name: " << name << ", Roll No: " << rollNo << endl;
    }
    // Static function to get student count
    static void showCount() {
        cout << "Total number of students: " << studentCount << endl;
    }
};
// Definition and initialization of static member
int Student::studentCount = 0;
// Main function
int main() {
    Student::showCount(); // Calling static function without object
    Student s1("Vivek", 101);
    Student s2("Anjali", 102);
    Student s3("Rohan", 103);
    s1.display();
    s2.display();
    s3.display();
    Student::showCount(); // Static function to display total count
    return 0;
}

🔍 Output Explanation
Total number of students: 0  
Name: Vivek, Roll No: 101  
Name: Anjali, Roll No: 102  
Name: Rohan, Roll No: 103  
Total number of students: 3

• Before creating any objects, `studentCount` is 0.
• After creating 3 student objects, the count becomes 3.
• The static data member `studentCount` keeps track of the number of students.
• The static function `showCount()` accesses this shared data and is called using the class name, not an object.

📝 Conclusion
Static data members and static functions provide a powerful mechanism to manage shared data across all objects of a class in C++. They are often used to:

• Track the number of objects created
• Share configuration or constants
• Group utility functions within classes

Using static members efficiently can lead to cleaner and more memory-optimized code in C++. Practice these concepts by modifying the example — try adding a function to reset the count, or create more student objects dynamically.