Two-dimensional arrays in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a 2D array of integers with 3 rows and 4 columns.

C

int arr[3][[1]];

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A4

B3

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3 instead of 4 for the number of columns.

Confusing rows and columns sizes.

The second dimension size is 4, so the array has 3 rows and 4 columns.

2fill in blank

medium

Complete the code to access the element in the second row and third column of a 2D array named matrix.

C

int value = matrix[[1]][2];

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A1

B2

C3

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 2 instead of 1 for the row index.

Confusing row and column indices.

Array indices start at 0, so the second row is index 1.

3fill in blank

hard

Fix the error in the code to correctly initialize a 2D array with 2 rows and 3 columns.

C

int arr[2][3] = {{ {1, 2, 3}, [1] }};

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A{3, 4, 5, 6}

B{7, 8}

C{1, 2}

D{4, 5, 6}

Attempts:

3 left

💡 Hint

Common Mistakes

Using fewer or more elements than columns in a row.

Missing braces around the second row.

The second row must have exactly 3 elements, so {4, 5, 6} is correct.

4fill in blank

hard

Fill both blanks to complete the nested loop that prints all elements of a 2D array named grid with 3 rows and 2 columns.

C

for(int i = 0; i < [1]; i++) {
    for(int j = 0; j < [2]; j++) {
        printf("%d ", grid[i][j]);
    }
    printf("\n");
}

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A3

B2

C4

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping rows and columns counts.

Using wrong loop limits causing out-of-bounds access.

The outer loop runs over rows (3), the inner loop over columns (2).

5fill in blank

hard

Fill all three blanks to create a 2D array named matrix with 2 rows and 3 columns, initialize it, and print the element at first row, second column.

C

int matrix[[1]][[2]] = {{ {1, 2, 3}, {4, 5, 6} }};
printf("%d\n", matrix[[3]][1]);

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

A2

B3

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong sizes for rows or columns.

Using 1 instead of 0 for the first row index.

The array has 2 rows and 3 columns. The first row index is 0, so matrix[0][1] prints the second element of the first row.