Procedural vs OOP approach in C++ - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of procedural code for area calculation

What is the output of this procedural C++ code that calculates the area of a rectangle?

C++

#include <iostream>

int calculateArea(int width, int height) {
    return width * height;
}

int main() {
    int w = 5, h = 3;
    std::cout << calculateArea(w, h) << std::endl;
    return 0;
}

A 53

B 8

C 15

D Compilation error

💡 Hint

Multiply width by height to get the area.

The function multiplies 5 (width) by 3 (height), resulting in 15.

❓ Predict Output

intermediate

Output of OOP code for area calculation

What is the output of this C++ code using a class to calculate the area of a rectangle?

C++

#include <iostream>

class Rectangle {
public:
    int width, height;
    int area() {
        return width * height;
    }
};

int main() {
    Rectangle rect;
    rect.width = 5;
    rect.height = 3;
    std::cout << rect.area() << std::endl;
    return 0;
}

A 15

B Compilation error

C 8

D 0

💡 Hint

The area method multiplies width and height stored in the object.

The Rectangle object has width 5 and height 3, so area() returns 15.

🧠 Conceptual

advanced

Difference in data handling between procedural and OOP

Which statement best describes how data is handled differently in procedural programming compared to object-oriented programming?

A Procedural programming bundles data and functions inside objects, while OOP keeps data and functions separate.

B Procedural programming organizes code around functions and data separately, while OOP bundles data and functions together inside objects.

C Both procedural and OOP always keep data and functions separate without any bundling.

D OOP does not use functions, only data, while procedural programming uses only functions.

💡 Hint

Think about how classes group data and behavior.

Procedural code treats data and functions separately; OOP groups them inside objects (classes).

🔧 Debug

advanced

Identify error in OOP code

What error will this C++ code produce?

C++

#include <iostream>

class Circle {
public:
    double radius;
    double area() {
        return 3.14 * radius * radius;
    }
};

int main() {
    Circle c;
    std::cout << c.area() << std::endl;
    return 0;
}

A Outputs 0

B Runtime error: division by zero

C Compilation error: radius not initialized

D Outputs garbage value

💡 Hint

Consider what value radius has before assignment.

The radius variable is uninitialized, so area() uses an undefined value, causing garbage output.

❓ Predict Output

expert

Output of mixed procedural and OOP code

What is the output of this C++ code that mixes procedural and OOP styles?

C++

#include <iostream>

class Counter {
public:
    int count = 0;
    void increment() { count++; }
};

void incrementCounter(Counter &c) {
    c.increment();
}

int main() {
    Counter c;
    incrementCounter(c);
    incrementCounter(c);
    std::cout << c.count << std::endl;
    return 0;
}

A 2

B 1

C 0

D Compilation error

💡 Hint

Each call to incrementCounter calls the object's increment method once.

The Counter object starts at 0, incremented twice, so count is 2.