Access modifiers (public, private, internal) in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code with access modifiers?

Consider the following C# code. What will be printed when Main runs?

C Sharp (C#)

class MyClass {
    private int secret = 42;
    public int GetSecret() {
        return secret;
    }
}

class Program {
    static void Main() {
        MyClass obj = new MyClass();
        System.Console.WriteLine(obj.GetSecret());
    }
}

A Compilation error due to private field access

B 0

C 42

D Runtime error

💡 Hint

Remember that private fields can be accessed inside the same class.

The private field secret is accessed inside MyClass through the public method GetSecret(). So, the output is 42.

❓ Predict Output

intermediate

What happens when accessing an internal member from another assembly?

Assume ClassA is in Assembly1 and ClassB is in Assembly2. ClassA has an internal method InternalMethod(). What happens if ClassB tries to call InternalMethod()?

C Sharp (C#)

public class ClassA {
    internal void InternalMethod() {
        System.Console.WriteLine("Hello from internal method");
    }
}

public class ClassB {
    public void Call() {
        ClassA a = new ClassA();
        a.InternalMethod();
    }
}

A Compilation error: 'InternalMethod' is inaccessible due to its protection level

B Prints: Hello from internal method

C Runtime error: Method not found

D Silent failure, no output

💡 Hint

Internal members are accessible only within the same assembly.

The internal method is not accessible from another assembly, so the compiler prevents access.

🔧 Debug

advanced

Why does this code cause a compilation error?

Look at the code below. Why does it fail to compile?

C Sharp (C#)

class Example {
    private int value = 10;
}

class Derived : Example {
    void Show() {
        System.Console.WriteLine(value);
    }
}

A Because 'Show' method is missing access modifier

B Because 'Derived' class must be declared public

C Because 'value' is not initialized

D Because 'value' is private and not accessible in the derived class

💡 Hint

Think about how private members behave with inheritance.

Private members are only accessible within the class they are declared in, not in derived classes.

🧠 Conceptual

advanced

Which access modifier allows access only within the same assembly and derived classes?

Choose the correct access modifier that allows a member to be accessed within the same assembly and also by derived classes outside the assembly.

A protected internal

B private

C internal

D public

💡 Hint

Think about combining 'protected' and 'internal' access.

protected internal allows access within the same assembly and also to derived classes outside the assembly.

❓ Predict Output

expert

What is the output of this code with nested classes and access modifiers?

Analyze the code and determine what will be printed when Main runs.

C Sharp (C#)

public class Outer {
    private int x = 5;
    public class Inner {
        public void Print(Outer o) {
            System.Console.WriteLine(o.x);
        }
    }
}

class Program {
    static void Main() {
        Outer outer = new Outer();
        Outer.Inner inner = new Outer.Inner();
        inner.Print(outer);
    }
}

A Runtime error

B 5

C 0

D Compilation error: 'x' is inaccessible

💡 Hint

Remember that nested classes can access private members of the outer class instance.

The nested class Inner can access private members of its containing class Outer through an instance.