C++ Program to Count Objects Using Static Variable with Explanation
C++
Easy
Classes & Objects
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1 min read
197 words
This problem helps you practice core C++ fundamentals in a practical way. It builds intuition around object, static, variable. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Use static member variable to count total objects created of a class. This teaches static member concept.
Logic: Static variable is shared by all objects
Input Format
No user input.
Objects of a class are created in the program.
Output Format
Total number of objects created.
Constraints
• Use a static member variable
• Static variable is shared by all objects
Concept Explanation
A static member variable belongs to the class, not to any single object.
So all objects share the same variable.
Step-by-Step Logic
1.Create a class.
2.Declare a static integer inside the class (for example count).
3.Initialize the static variable outside the class.
4.In the constructor:
• Increment count by 1.
5.Every time an object is created, constructor runs and count increases.
6.Use a static member function or direct access to print count.
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
class Counter {
public:
static int count;
Counter() {
count++;
}
};
int Counter::count = 0;
void question5_static_count() {
Counter c1, c2, c3;
cout << "Total objects created: " << Counter::count << endl;
}
Output Example
Output:
Total objects = 3
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Use static member variable to count total objects created of a class. This teaches static member concept.
Logic: Static variable is shared by all objects
Input / Output
Input
No user input.
Objects of a class are created in the program.
Output
Total number of objects created.
Constraints
• Use a static member variable
• Static variable is shared by all objects
Examples
Output:
Total objects = 3
Explanation
Concept Explanation
A static member variable belongs to the class, not to any single object.
So all objects share the same variable.
Step-by-Step Explanation
1.Create a class.
2.Declare a static integer inside the class (for example count).
3.Initialize the static variable outside the class.
4.In the constructor:
• Increment count by 1.
5.Every time an object is created, constructor runs and count increases.
6.Use a static member function or direct access to print count.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
class Counter {
public:
static int count;
Counter() {
count++;
}
};
int Counter::count = 0;
void question5_static_count() {
Counter c1, c2, c3;
cout << "Total objects created: " << Counter::count << endl;
}
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