Access specifiers in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of accessing private member in derived class

What is the output of this C++ code?

C++

#include <iostream>
using namespace std;

class Base {
private:
    int x = 10;
public:
    int getX() { return x; }
};

class Derived : public Base {
public:
    void printX() {
        // cout << x << endl; // line A
        cout << getX() << endl;
    }
};

int main() {
    Derived d;
    d.printX();
    return 0;
}

A 0

B Compilation error due to accessing private member x

C 10

D Runtime error

💡 Hint

Private members are not accessible directly in derived classes, but public methods can access them.

The private member 'x' is not accessible directly in Derived, so line A is commented out. Instead, the public method getX() returns the value 10, which is printed.

❓ Predict Output

intermediate

Output of protected member access in derived class

What will this program print?

C++

#include <iostream>
using namespace std;

class Parent {
protected:
    int val = 5;
};

class Child : public Parent {
public:
    void show() {
        cout << val << endl;
    }
};

int main() {
    Child c;
    c.show();
    return 0;
}

A Compilation error: val is inaccessible

B 5

C 0

D Runtime error

💡 Hint

Protected members are accessible in derived classes.

The protected member 'val' is accessible in the derived class Child, so printing val outputs 5.

❓ Predict Output

advanced

Accessing private member from outside class

What error does this code produce?

C++

#include <iostream>
using namespace std;

class Sample {
private:
    int secret = 42;
};

int main() {
    Sample s;
    cout << s.secret << endl;
    return 0;
}

A Compilation error: 'secret' is private within this context

B 42

C Runtime error

D 0

💡 Hint

Private members cannot be accessed outside their class.

The member 'secret' is private and cannot be accessed directly from main, causing a compilation error.

❓ Predict Output

advanced

Output of mixed access specifiers in inheritance

What is the output of this program?

C++

#include <iostream>
using namespace std;

class A {
public:
    int x = 1;
protected:
    int y = 2;
private:
    int z = 3;
};

class B : public A {
public:
    void print() {
        cout << x << ' ' << y << ' ';
        // cout << z << ' '; // line X
    }
};

int main() {
    B b;
    b.print();
    return 0;
}

A Compilation error due to accessing private member z

B 1 2 3

C Runtime error

D 1 2

💡 Hint

Private members are not accessible in derived classes.

The public member x and protected member y are accessible in B, but private member z is not. The commented line X would cause a compilation error if uncommented.

🧠 Conceptual

expert

Number of accessible members in derived class

Given the class below, how many members are accessible directly in class Derived?

C++

class Base {
public:
    int a;
protected:
    int b;
private:
    int c;
};

class Derived : public Base {
    void func() {
        // Which members can be accessed here?
    }
};

A 2 members: a and b

B 3 members: a, b, and c

C 1 member: a only

D 0 members

💡 Hint

Private members are not accessible in derived classes.

In public inheritance, public and protected members of Base are accessible in Derived. Private members are not accessible.