C# Exception MCQs

Question 1: Which of the following is the base class for all types of exceptions?

Answer: D

The System.Exception class is the base class for all the exceptions in .NET Framework.

Question 2: Which of the following statement is TRUE?

Answer: B

All the runtime errors are called exceptions and compile-time errors called errors.

Question 3: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
    Console.Write(arr[10]);
    Console.WriteLine("End of Program");
}

Answer: B

It throws an IndixOutOfRange exception and terminates the execution of the remaining program. This is why we need to handle exception to prevent the unexpected termination of the program. Learn exception handling in C#.

Question 4: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
    
    try
    {
        Console.Write(arr[10]);
    }    
    catch(Exception ex)
    {
        Console.WriteLine("Error occurred!");
    }

    Console.WriteLine("Execute remaining program..");		
}

Answer: B

Since it handles all kinds of exception using catch() block, it will not be terminated and execute the catch block and also continue the execution of the remaining code after the catch block. If the finally block follows the catch block then all the code after the finally block will be executed. Learn exception handling in C#.

Question 5: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
	try
    {
        Console.Write(arr[5]);
    }    
    catch(NullReferenceException  ex)
    {
        Console.WriteLine("Error occurred!");
    }
	Console.WriteLine("Execute remaining program");
}

Answer: C.

arr[5] will raise IndexOutOfRangeException exception and the catch block handles only NullReferenceExceptio, so this exception will not be handled and program will be terminated. Learn exception handling in C#.

Question 6: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
    try{
        Console.Write(arr[10]);
    }
    catch(IndexOutOfRangeException  ex){
        Console.WriteLine("Index error occurred!");
    }
    catch(NullReferenceException  ex){
        Console.WriteLine("Null error occurred!");
    }
    catch(Exception ex){
        Console.WriteLine("Error occurred!");
    }
}

Answer: C

arr[10] will raise an IndexOutOfRangeException, so the catch block which handles IndexOutOfRangeException will be executed, not any other catch blocks. The general catch block will not be executed because it is the last block. Learn exception handling in C#.

Question 7: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
	try{
        Console.Write(arr[10]);
    }
    catch(Exception ex){
		Console.WriteLine("Error occurred!");
	}
	catch(IndexOutOfRangeException  ex){
        Console.WriteLine("Index error occurred!");
    }
    catch(NullReferenceException  ex){
        Console.WriteLine("Null error occurred!");
    }
}

Answer:D

This will give a compile-time error because the catch(Exception ex) block must be the last block among multiple catch blocks. Learn exception handling in C#.

Question 8: What will be the output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
	try{
        Console.Write(arr[10]);
    }
    catch(Exception ex){
        Console.WriteLine("Error occurred!");
    }
    finally
    {
        Console.WriteLine("Executing finally block");
    }
	
	Console.WriteLine("Executing remaining program.");
}

Answer: A, B, D

Above, an exception will be handled in the catch block, and then finally block will be executed, and then the remaining program will be executed. Learn exception handling in C#.

Question 9: Select the correct output of the following program?

public static void Main()
{
    int[] arr = {1, 2, 3, 4, 5};
    try{
        try{
            Console.Write(arr[10]);
        }
		catch(NullReferenceException ex){
			Console.WriteLine("Null error occurred!");
		}
        catch(Exception ex){
			Console.WriteLine("Error occurred!");
		}
	}
	catch(Exception ex){
		Console.WriteLine("Handling exception.");
	}
	Console.WriteLine("Execute remaining program.");
}

Answer: C, E

In C#, if the inner catch block does not catch the exception, then it will be handled in the outer catch block. Learn exception handling in C#.

Question 10: What will be the output of the following program? 

public static void Main()
{            
	int val = GetVal();
}
	
public static int GetVal(){
	int[] arr = {1, 2, 3, 4, 5};
    
    try{
        return arr[10];
    }
    catch(Exception ex){
        Console.WriteLine("Error occurred!");
    }
    finally{
	    return 0;
	}
}

Answer: B

The finally block cannot contain the return or break statement because it does not allow to leave the control. Learn exception handling in C#.