Multiple catch blocks in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of multiple catch blocks with specific exceptions

What is the output of this C# code when an IndexOutOfRangeException is thrown?

C Sharp (C#)

using System;

class Program {
    static void Main() {
        try {
            int[] arr = new int[2];
            Console.WriteLine(arr[5]);
        }
        catch (NullReferenceException) {
            Console.WriteLine("Null reference caught");
        }
        catch (IndexOutOfRangeException) {
            Console.WriteLine("Index out of range caught");
        }
        catch (Exception) {
            Console.WriteLine("General exception caught");
        }
    }
}

A Index out of range caught

B No output, program crashes

C Null reference caught

D General exception caught

💡 Hint

Think about which catch block matches the thrown exception type exactly.

The thrown exception is IndexOutOfRangeException, so the catch block for that specific exception runs, printing "Index out of range caught".

❓ Predict Output

intermediate

Which catch block executes for a NullReferenceException?

Given this code, what will be printed when a NullReferenceException occurs?

C Sharp (C#)

using System;

class Program {
    static void Main() {
        try {
            string s = null;
            Console.WriteLine(s.Length);
        }
        catch (ArgumentException) {
            Console.WriteLine("Argument exception caught");
        }
        catch (NullReferenceException) {
            Console.WriteLine("Null reference caught");
        }
        catch (Exception) {
            Console.WriteLine("General exception caught");
        }
    }
}

A No output, program crashes

B General exception caught

C Argument exception caught

D Null reference caught

💡 Hint

Which catch block matches the exception type exactly?

NullReferenceException is caught by the matching catch block, so it prints "Null reference caught".

❓ Predict Output

advanced

Output when multiple catch blocks could match

What will this code print when a FormatException is thrown?

C Sharp (C#)

using System;

class Program {
    static void Main() {
        try {
            int.Parse("abc");
        }
        catch (FormatException) {
            Console.WriteLine("Format exception caught");
        }
        catch (Exception) {
            Console.WriteLine("General exception caught");
        }
    }
}

A Format exception caught

B No output, program crashes

C Compilation error due to catch order

D General exception caught

💡 Hint

Check the order of catch blocks and C# rules about exception handling.

In C#, catch blocks must be ordered from most specific to most general. Catching Exception before FormatException causes a compile-time error.

❓ Predict Output

advanced

Which catch block handles AggregateException?

What will be printed when this code throws an AggregateException?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static void Main() {
        try {
            Task.WaitAll(Task.Run(() => throw new InvalidOperationException()));
        }
        catch (InvalidOperationException) {
            Console.WriteLine("Invalid operation caught");
        }
        catch (AggregateException) {
            Console.WriteLine("Aggregate exception caught");
        }
        catch (Exception) {
            Console.WriteLine("General exception caught");
        }
    }
}

A Invalid operation caught

B Aggregate exception caught

C General exception caught

D No output, program crashes

💡 Hint

Task.WaitAll wraps exceptions in AggregateException.

Task.WaitAll throws AggregateException which is caught by the matching catch block printing "Aggregate exception caught".

🧠 Conceptual

expert

Order of multiple catch blocks and exception handling

Which statement about multiple catch blocks in C# is correct?

A Catch blocks must be ordered from most specific to most general exception types to compile.

B Catch blocks must be ordered from most general to most specific exception types.

C Catch blocks can be in any order; the first matching block executes at runtime.

D Only one catch block is allowed per try block in C#.

💡 Hint

Think about how C# compiler checks catch block order.

C# requires catch blocks to be ordered from most specific to most general exception types to avoid unreachable code errors.