Multidimensional arrays
- C course
- Beginner
- Lesson 56/116
- 5 min
Learn multidimensional arrays as matrices with int[][].
Multidimensional arrays
A two-dimensional array in C holds data in matrix form. The declaration uses two pairs of brackets: first rows, then columns.
int matrix[2][3] = {
{1, 2, 3},
{4, 5, 6}
};Here matrix is a 2-row × 3-column table. matrix[0][0] is 1, matrix[1][2] is 6. The first index selects the row, the second the column. Nested braces group rows.
Accessing matrix elements
You access a 2D array element with matrix[row][column]. Each index starts at 0.
int matrix[2][3] = {
{1, 2, 3},
{4, 5, 6}
};
printf("%d\n", matrix[0][2]); // 3
printf("%d\n", matrix[1][0]); // 4Row 0, column 2 = 3. Row 1, column 0 = 4. To traverse matrices you use nested loops; the outer iterates rows, the inner columns.
Practice Print matrix elements
Write a C program. Declare int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};. Print the top-left and bottom-right elements with printf("%d %d\n", matrix[0][0], matrix[1][2]);. Put #include <stdio.h> at the top.
Starter code
#include <stdio.h>
int main(void) {
// Declare matrix, print two elements
return 0;
}Sample solution
#include <stdio.h>
int main(void) {
int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};
printf("%d %d\n", matrix[0][0], matrix[1][2]);
return 0;
}Expected output
1 6
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How many elements does int matrix[2][3] hold?
int matrix[2][3];- 6 Correct answer
- 2
- 3
- 5
Explanation: Dimensions are multiplied.
2 Access the second element
printf("%d
", matrix[0][____]);printf("%d
", matrix[0][1]);Explanation: matrix[0][1] is the second element of the first row.
3 Match the matrix concepts
| Term | Meaning |
|---|---|
matrix[0][0] |
Top left |
matrix[1][2] |
Bottom right |
[2][3] |
2 rows 3 cols |
{1,2,3} |
One row |