Array indexing and access in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the first element of the array.

C Sharp (C#)

int[] numbers = {1, 2, 3, 4};
int first = numbers[[1]];

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

A0

B1

C4

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 as the first index instead of 0.

Using a negative index which is invalid.

Arrays in C# start at index 0, so the first element is at index 0.

2fill in blank

medium

Complete the code to access the last element of the array using its length.

C Sharp (C#)

int[] values = {10, 20, 30, 40, 50};
int last = values[values.Length [1] 1];

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

A+

B/

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using +1 which causes an index out of range error.

Using multiplication or division instead of subtraction.

The last element is at index Length - 1 because indexing starts at 0.

3fill in blank

hard

Fix the error in accessing the third element of the array.

C Sharp (C#)

string[] fruits = {"apple", "banana", "cherry"};
string third = fruits[[1]];

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

A3

B2

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3 as index which is out of range.

Using 1 or 0 which points to earlier elements.

The third element is at index 2 because indexing starts at 0.

4fill in blank

hard

Fill both blanks to create an array of squares for numbers 1 to 5.

C Sharp (C#)

int[] squares = new int[5];
for (int i = 0; i [1] 4; i++) {
    squares[i] = (i [2] 1) * (i [2] 1);
}

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

A<=

B<

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of <= causes missing the last element.

Subtracting 1 instead of adding 1 changes the numbers incorrectly.

The loop runs while i is less than or equal to 4 (indexes 0 to 4). To get numbers 1 to 5, add 1 to i before squaring.

5fill in blank

hard

Fill all three blanks to create a reversed copy of the array.

C Sharp (C#)

int[] original = {1, 2, 3, 4};
int[] reversed = new int[original.Length];
for (int [1] = 0; [1] < original.Length; [1]++) {
    reversed[[2]] = original[original.Length [3] 1 - [1]];
}

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

Ai

Boriginal.Length - 1 - i

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong loop variable names inconsistently.

Incorrect calculation of reversed index causing errors.

Use 'i' as the loop variable. Assign reversed[i] to original at the reversed index calculated by Length - 1 - i.