Getter and setter methods in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of getter and setter usage in C++ class

What is the output of this C++ program that uses getter and setter methods?

C++

#include <iostream>
class Box {
private:
    int length;
public:
    void setLength(int l) {
        length = l;
    }
    int getLength() {
        return length;
    }
};

int main() {
    Box b;
    b.setLength(10);
    std::cout << b.getLength() << std::endl;
    return 0;
}

A 10

B 0

C Compilation error

D Garbage value

💡 Hint

Check what value is assigned by the setter before calling the getter.

The setter sets the private variable length to 10. The getter returns this value, so the output is 10.

❓ Predict Output

intermediate

Effect of missing setter call on getter output

What will this program print if the setter is never called?

C++

#include <iostream>
class Box {
private:
    int length = 5;
public:
    void setLength(int l) {
        length = l;
    }
    int getLength() {
        return length;
    }
};

int main() {
    Box b;
    std::cout << b.getLength() << std::endl;
    return 0;
}

A 0

B 5

C Compilation error

D Garbage value

💡 Hint

Look at the default value of the private variable.

The private variable length is initialized to 5. Since the setter is not called, the getter returns 5.

🔧 Debug

advanced

Identify the error in getter and setter methods

What error will this code produce when compiled?

C++

#include <iostream>
class Box {
private:
    int length;
public:
    void setLength(int l) {
        length = l;
    }
    int getLength() const {
        return length;
    }
};

int main() {
    Box b;
    b.setLength(7);
    std::cout << b.getLength() << std::endl;
    return 0;
}

A No error, output is 7

B Runtime error: uninitialized variable

C Compilation error: calling non-const method on const object

D Compilation error: cannot call non-const setter from const method

💡 Hint

Check if const correctness is properly used.

The getter is marked const, which is allowed. The setter is non-const, but it is called on a non-const object. The code compiles and outputs 7.

📝 Syntax

advanced

Which option causes a compilation error in getter/setter?

Which of the following setter method definitions will cause a compilation error?

A void setLength(int l) { length = l; }

B void setLength(int l) override { length = l; }

C void setLength(int l) noexcept { length = l; }

D void setLength(int l) const { length = l; }

💡 Hint

Consider what const means for member functions.

A setter modifies the object, so it cannot be marked const. Option D tries to modify length inside a const method, causing a compilation error.

🚀 Application

expert

Determine the final value after multiple setter calls

Given the following code, what is the final output?

C++

#include <iostream>
class Counter {
private:
    int count = 0;
public:
    void setCount(int c) {
        if (c >= 0) {
            count = c;
        }
    }
    int getCount() {
        return count;
    }
};

int main() {
    Counter c;
    c.setCount(5);
    c.setCount(-3);
    c.setCount(10);
    std::cout << c.getCount() << std::endl;
    return 0;
}

A 5

B -3

C 10

D 0

💡 Hint

Notice the condition inside the setter method.

The setter only updates count if the new value is zero or positive. The call with -3 is ignored. The final value set is 10.