Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Count the number of objects using Static member function in C++ Program
The goal here is to count the number of objects of a class that are being created using a static member function.
A static data member is shared by all objects of the class commonly. If no value is given, a static data member is always initialized with 0.
A static member function can only use static data members of that class.
We are using a class Student here. We will declare a static data member count which will store the count of objects. A static member function rollCall(void) which will display the count of objects as roll no.s of students in a class.
Approach used in the below program is as follows
We declare a class Student which has public data members int rollno and static data member count.
There is a constructor which calls rollcall() and initializes rollno with count.
There is a destructor which decreases count.
Static member function rollcall() displays the count of objects as Student count and increments the count.
Each time the object of Student is created, constructor calls rollcall() and count is incremented. This count is assigned to rollno of that Student object.
In the main we created 4 objects of class Student as stu1,stu2,stu3,stu4 and verified that count and rollno is the same as no. of objects.
Example
// C++ program to Count the number of objects
// using the Static member function
#include <iostream>
using namespace std;
class Student {
public:
int rollno;
static int count;
public:
Student(){
rollCall();
rollno=count;
}
~Student()
{ --count; }
static void rollCall(void){
cout <<endl<<"Student Count:" << ++count<< "\n"; //object count
}
};
int Student::count;
int main(){
Student stu1;
cout<<"Student 1: Roll No:"<<stu1.rollno;
Student stu2;
cout<<"Student 2: Roll No:"<<stu2.rollno;
Student stu3;
cout<<"Student 3: Roll No:"<<stu3.rollno;
Student stu4;
cout<<"Student 4: Roll No:"<<stu4.rollno;
return 0;
}Output
If we run the above code it will generate the following output −
Student Count:1 Student 1: Roll No:1 Student Count:2 Student 2: Roll No:2 Student Count:3 Student 3: Roll No:3 Student Count:4 Student 4: Roll No:4
852 Views
To Continue Learning Please Login