Array bounds checking behavior in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of accessing array element within bounds

What is the output of this C# code snippet?

C Sharp (C#)

int[] numbers = {10, 20, 30};
Console.WriteLine(numbers[1]);

A 20

B 10

C 30

D IndexOutOfRangeException

💡 Hint

Remember that array indexing in C# starts at 0.

The array 'numbers' has elements 10 at index 0, 20 at index 1, and 30 at index 2. Accessing numbers[1] returns 20.

❓ Predict Output

intermediate

Output when accessing array element out of bounds

What happens when this C# code runs?

C Sharp (C#)

int[] arr = new int[3] {1, 2, 3};
Console.WriteLine(arr[3]);

A Throws IndexOutOfRangeException

B Prints 3

C Prints null

D Prints 0

💡 Hint

Check if the index 3 is valid for an array of length 3.

Array indices go from 0 to length-1. Index 3 is outside the valid range, so an IndexOutOfRangeException is thrown.

🔧 Debug

advanced

Identify the cause of runtime error in array access

Why does this code throw an exception at runtime?

C Sharp (C#)

string[] fruits = {"apple", "banana", "cherry"};
for (int i = 0; i < fruits.Length; i++)
{
    Console.WriteLine(fruits[i]);
}

A The array is not initialized properly

B The loop condition should be i < fruits.Length, not i <= fruits.Length

C The Console.WriteLine statement is incorrect

D The variable i is not declared

💡 Hint

Check the loop boundary condition carefully.

The loop runs from i = 0 to i = fruits.Length inclusive. Since fruits.Length is 3, accessing fruits[3] causes an IndexOutOfRangeException.

🧠 Conceptual

advanced

Array bounds checking behavior in C#

Which statement best describes how C# handles array bounds checking?

A C# checks array bounds only in debug mode but not in release mode

B C# does not check array bounds and accessing invalid indices causes silent memory corruption

C C# automatically checks array bounds at runtime and throws an exception if an invalid index is accessed

D C# requires the programmer to manually check array bounds before accessing elements

💡 Hint

Think about safety features of C# compared to languages like C or C++.

C# performs automatic bounds checking on arrays at runtime and throws IndexOutOfRangeException if an invalid index is accessed.

❓ Predict Output

expert

Output of multi-dimensional array access with invalid index

What is the output or result of running this C# code?

C Sharp (C#)

int[,] matrix = new int[2, 2] { {1, 2}, {3, 4} };
Console.WriteLine(matrix[1, 2]);

A Prints 4

B Prints 0

C Compilation error

D Throws IndexOutOfRangeException

💡 Hint

Check the valid indices for a 2x2 array.

The valid indices for a 2x2 array are 0 and 1 for both dimensions. Accessing matrix[1, 2] is out of bounds and throws an IndexOutOfRangeException.