C Multi-Dimensional Array

A multi-dimensional array in C is an array that contains other arrays as its elements. It is like an array of arrays. The most common type of multi-dimensional array is a 2D array, but you can also have 3D, 4D, etc.

In simple terms, a multi-dimensional array lets you store data in rows and columns (like a table or grid).

Syntax:


type arrayName[size1][size2];

Explanation:

type: The data type of the elements in the array (e.g., int, float).
size1: The number of rows.
size2: The number of columns.

Example: 2D Array


#include <stdio.h>

int main() {
    // Declare a 2D array (matrix) with 2 rows and 3 columns
    int arr[2][3] = {{10, 20, 30}, {40, 50, 60}};

    // Access and print elements of the 2D array
    printf("Element at arr[0][0]: %d\n", arr[0][0]);  // Output: 10
    printf("Element at arr[0][1]: %d\n", arr[0][1]);  // Output: 20
    printf("Element at arr[1][2]: %d\n", arr[1][0]);  // Output: 40

    // Loop through the 2D array to print all elements
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            printf("arr[%d][%d] = %d\n", i, j, arr[i][j]);
        }
    }

    return 0;
}

Output:

Element at arr[0][0]: 10
Element at arr[0][1]: 20
Element at arr[1][2]: 40
arr[0][0] = 10
arr[0][1] = 20
arr[0][2] = 30
arr[1][0] = 40
arr[1][1] = 50
arr[1][2] = 60

Explanation:

int arr[2][3]: This declares a 2D array with 2 rows and 3 columns.
{ {1, 2, 3}, {4, 5, 6} }: Initializes the array with values. The first row is {1, 2, 3}, and the second row is {4, 5, 6}.
We can access elements like arr[0][0] (first row, first column), arr[1][2] (second row, third column), etc.

C Multi-Dimensional Array – Interview Questions

Q 1: What is a multi-dimensional array?

Ans: An array with more than one dimension, such as a 2D array.

Q 2: How do you declare a 2D array in C?

Ans: int arr[3][4];

Q 3: How is memory stored in a 2D array?

Ans: In row-major order.

Q 4: Where are multi-dimensional arrays used?

Ans: In matrices, tables, and grid-based problems.

Q 5: How do you access elements of a 2D array?

Ans: Using row and column indices, e.g., arr[i][j].