Multidimensional arrays

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]);  // 4

Row 0, column 2 = 3. Row 1, column 0 = 4. To traverse matrices you use nested loops; the outer iterates rows, the inner columns.

Exercise 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.

Show example 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;
}

Test yourself

How many elements does int matrix[2][3] hold?
```
int matrix[2][3];
```
- 6
- 2
- 3
- 5
Show answer

6 — Dimensions are multiplied.

Access the second element

printf("%d
", matrix[0][____]);

Show answer

printf("%d
", matrix[0][1]);

Match the matrix concepts

matrix[0][0]

Top left
matrix[1][2]

Bottom right
[2][3]

2 rows 3 cols
{1,2,3}

One row

Next lesson: Arrays and loops

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