Array Deletion at End in DSA C# - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to remove the last element from the array by reducing its size.

DSA C#

int[] arr = {1, 2, 3, 4, 5};
int size = arr.Length;
size = size [1] 1;

Drag options to blanks, or click blank then click option'

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' to change the size.

Trying to multiply or divide the size.

To delete the last element, we reduce the size by 1 using subtraction.

2fill in blank

medium

Complete the code to print the array elements after deleting the last element.

DSA C#

for (int i = 0; i < [1]; i++) {
    Console.Write(arr[i] + " ");
}
Console.WriteLine();

Drag options to blanks, or click blank then click option'

Asize

Barr.Length

Carr

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using arr.Length which prints all elements including the deleted one.

Using the array name instead of size in the loop condition.

We use the updated size variable to print only the elements before the deleted one.

3fill in blank

hard

Fix the error in the code that tries to delete the last element by setting it to zero.

DSA C#

int[] arr = {1, 2, 3, 4, 5};
int size = arr.Length;
arr[size [1] 1] = 0;
size = size - 1;

Drag options to blanks, or click blank then click option'

A*

B-

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' causes index out of range error.

Using '*' or '/' is invalid for indexing.

To access the last element, subtract 1 from size because array indices start at 0.

4fill in blank

hard

Fill both blanks to correctly delete the last element and print the updated array.

DSA C#

int[] arr = {10, 20, 30, 40};
int size = arr.Length;
arr[size [1] 1] = 0;
size = size [2] 1;
for (int i = 0; i < size; i++) {
    Console.Write(arr[i] + " ");
}

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' in either blank causes errors or wrong output.

Using '*' or '/' is invalid for these operations.

Both blanks use '-' to access the last element and reduce the size by one.

5fill in blank

hard

Fill all three blanks to delete the last element, update size, and print the array elements.

DSA C#

int[] arr = {5, 15, 25, 35, 45};
int size = arr.Length;
arr[size [1] 1] = 0;
size = size [2] 1;
for (int [3] = 0; i < size; i++) {
    Console.Write(arr[i] + " ");
}

Drag options to blanks, or click blank then click option'

A-

B+

Ci

Dj

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' for index or size.

Using 'j' as loop variable but condition uses 'i'.

Use '-' to access last element and reduce size, and 'i' as the loop variable.

Practice

1. What happens when you delete an element from the end of an array in C#?

easy

A. The array size remains the same but the last element is set to zero.

B. The first element is removed and the array size decreases by one.

C. All elements are shifted to the right.

D. The last element is removed and the array size decreases by one.

Solution

1. Step 1: Understand array deletion at end

   Deleting at the end means removing the last element only.

2. Step 2: Effect on array size

   Removing the last element reduces the array size by one.

3. Final Answer:

   The last element is removed and the array size decreases by one. -> Option D

4. Quick Check:

   Delete end element = size - 1 [OK]

Hint: Deleting at end removes last element and shrinks array [OK]

Common Mistakes:

• Thinking the first element is removed
• Assuming array size stays the same
• Believing elements shift right

2. Which of the following C# code snippets correctly deletes the last element from an array named arr?

easy

A. arr.Delete(arr.Length);

B. arr.RemoveAt(arr.Length - 1);

C. arr = arr.Take(arr.Length - 1).ToArray();

D. arr.Pop();

Solution

1. Step 1: Check valid array deletion methods

   Arrays in C# are fixed size; to delete last element, create new array excluding last.

2. Step 2: Analyze options

   arr = arr.Take(arr.Length - 1).ToArray(); uses LINQ Take to get all but last element and converts to array, which is correct.

3. Final Answer:

   arr = arr.Take(arr.Length - 1).ToArray(); -> Option C

4. Quick Check:

   Use Take and ToArray to delete last element [OK]

Hint: Use Take(arr.Length - 1).ToArray() to remove last element [OK]

Common Mistakes:

• Using RemoveAt on array (only for List)
• Calling Pop() on array (not supported)
• Using invalid Delete method

3. What is the output of the following C# code?

int[] arr = {10, 20, 30, 40};
arr = arr.Take(arr.Length - 1).ToArray();
Console.WriteLine(string.Join(", ", arr));

medium

A. 10, 20, 30

B. 10, 20, 30, 40

C. 20, 30, 40

D. 10, 20, 40

Solution

1. Step 1: Understand the Take method

   arr.Take(arr.Length - 1) takes first 3 elements: 10, 20, 30.

2. Step 2: Convert to array and print

   After conversion, arr has 3 elements: 10, 20, 30, printed with commas.

3. Final Answer:

   10, 20, 30 -> Option A

4. Quick Check:

   Take length-1 elements = 10, 20, 30 [OK]

Hint: Take length-1 elements to remove last [OK]

Common Mistakes:

• Printing original array without deletion
• Confusing which elements are taken
• Assuming last element remains

4. Identify the error in this C# code that tries to delete the last element of an array:

int[] arr = {1, 2, 3, 4};
arr.RemoveAt(arr.Length - 1);

medium

A. Arrays do not have RemoveAt method; use List instead.

B. RemoveAt index should be 0, not arr.Length - 1.

C. RemoveAt removes first element, not last.

D. RemoveAt requires two parameters.

Solution

1. Step 1: Check array methods

   Arrays in C# do not support RemoveAt; it's a List method.

2. Step 2: Correct approach

   To delete last element from array, create new array or use List instead.

3. Final Answer:

   Arrays do not have RemoveAt method; use List instead. -> Option A

4. Quick Check:

   RemoveAt not in array, only List [OK]

Hint: RemoveAt works on List, not array [OK]

Common Mistakes:

• Trying RemoveAt on array
• Wrong index for RemoveAt
• Assuming RemoveAt needs two parameters

5. You have an array int[] arr = {5, 10, 15, 20, 25};. Write C# code to delete the last two elements and print the resulting array.

hard

A. arr = arr.Take(2).ToArray(); Console.WriteLine(string.Join(", ", arr));

B. arr = arr.Take(arr.Length - 2).ToArray(); Console.WriteLine(string.Join(", ", arr));

C. arr = arr.Skip(2).ToArray(); Console.WriteLine(string.Join(", ", arr));

D. arr.RemoveRange(arr.Length - 2, 2); Console.WriteLine(string.Join(", ", arr));

Solution

1. Step 1: Remove last two elements using Take

   Take(arr.Length - 2) keeps first 3 elements: 5, 10, 15.

2. Step 2: Convert to array and print

   Convert to array and print elements separated by commas.

3. Final Answer:

   arr = arr.Take(arr.Length - 2).ToArray(); Console.WriteLine(string.Join(", ", arr)); -> Option B

4. Quick Check:

   Take length-2 elements = 5, 10, 15 [OK]

Hint: Use Take(length - 2) to remove last two elements [OK]

Common Mistakes:

• Using RemoveRange on array (only for List)
• Using Skip to remove from start instead of end
• Taking wrong number of elements