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C – Multi-Dimensional Array in C

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What is Multi-Dimensional Array in C?

In C programming, Multi-Dimensional Arrays refer to as array of arrays. This could be of 2D or 3D (two-dimensional or three-dimensional) Array. These arrays are stored in the form of a table (with rows and columns).

The general form of multi-dimensional array:

data-type array_name [size1][size2]...[sizeN];

The data type must be a valid C data type, a unique name must be specified to each array and the size must be of an integer constant.

Declaration of 2d and 3d Array in C.

int arr1[3][4]; //2D Array
OR
int arr2[3][4][3]; //3D Array

Initialization of multidimensional array.

We can initialize a Multi Dimensional Array (two-dimensional or three-dimensional) in the following ways in C.

1. Initialization of 2d Array

//Method1
//initializing with 5 rows and 3 columns
int arr[5][3] = {
        {1, 2, 3},
        {2, 3, 4},
        {3, 4, 5},
        {4, 5, 6}, 
        {7, 8, 9}
     };
OR
//Method2
int x[3][4] = {0, 1 ,2 ,3 ,4 , 5 , 6 , 7 , 8 , 9 , 10 , 11}

2. Initialization of 3d Array

//Method1
int arr[2][3][4] = {
    {{3, 4, 2, 3}, {0, -3, 9, 11}, {23, 12, 23, 2}},
    {{13, 4, 56, 3}, {5, 9, 3, 5}, {3, 1, 4, 9}}};
OR
//method2
int arr[2][3][4] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 
                 11, 12, 13, 14, 15, 16, 17, 18, 19,
                 20, 21, 22, 23};

Accessing Multi-Dimensional Array Elements in C

Accessing 2d Array:

An array can be accessed by using a specific index number. It can be achieved by placing the particular index number within the brackets [][]. Such as:

arr[2][3]; //the 4th element of the third row is accessed
arr[3][2]; //the 3rd element of the fourth row is accessed
OR
int val = arr[2][3]; // assigning the element to val

Accessing 3d Array:

Accessing 3-dimensional array is also as same as a two-dimensional array, the only difference is that in 3d array we have to specify 3 subscripts with a required index number.

Example of two -dimensional Array in C:

Displaying the elements with index number from 2D Arrays.

#include <stdio.h>

int main()
{
  //Array with 4 rows and 2 columns
  int arr[4][2] = {
    { 0, 1 },
    { 2, 3 },
    { 4, 5 },
    { 6, 7 }
  };

  int i, j;

  //Displaying the elements
  printf("Elements with index numbers:\n");
  for (i = 0; i < 4; i++)
  {
    for (j = 0; j < 2; j++)
    {
      printf("a[%d][%d] = %d\n", i, j, arr[i][j]);
    }
  }

  return 0;
}

Output: After executing the above code, the following result will be displayed.

arr[0][0]: 0
arr[0][1]: 1
arr[1][0]: 2
arr[1][1]: 3
arr[2][0]: 4
arr[2][1]: 5
arr[3][0]: 6
arr[3][1]: 7

Example of three-dimensional Array in C:

Displaying the elements with index number from 3D Arrays.

#include <stdio.h>

int main()
{
  int arr[2][3][2] = { 
        { {0,1}, {2,3}, {4,5} }, 
        { {6,7}, {8,9}, {10,11} } 
    };
  int i, j, k;

 // Display with index number
  printf("Elements with index number: \n");
  for (i = 0; i < 2; ++i)
  {
    for (j = 0; j < 3; ++j)
    {
      for (k = 0; k < 2; ++k)
      {
        printf("Element at [%d][%d][%d] = %d\n", i, j, k, arr[i][j][k]);
      }
    }
  }

  return 0;
}

Output: After executing the above code, the following result will be displayed.

Element at arr[0][0][0] = 0
Element at arr[0][0][1] = 1
Element at arr[0][1][0] = 2
Element at arr[0][1][1] = 3
Element at arr[0][2][0] = 4
Element at arr[0][2][1] = 5
Element at arr[1][0][0] = 6
Element at arr[1][0][1] = 7
Element at arr[1][1][0] = 8
Element at arr[1][1][1] = 9
Element at arr[1][2][0] = 10
Element at arr[1][2][1] = 11

As we saw the examples of 2D and 3D arrays, in a similar we can create any number dimension as required. However, the most used multidimensional array is a two-dimensional array.

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