Multidimensional Arrays

Arrays can be made multi-dimensional by adding more sets of square brackets. It can be two dimensional or three dimensional. The data is stored in tabular form (row ∗ column) which is also known as matrix.

A two dimensional array of data, is with one dimension representing each row and the second dimension representing each column. A three-dimensional array could be a cube, with one dimension representing width, a second dimension representing height, and a third dimension representing depth. We can even have arrays of more than three dimensions but they are more complex,

Declaring Multidimensional Arrays

When you declare arrays, each dimension is represented as a subscript in the array.

A two-dimensional array has two subscripts.

int grid[5, 13];

A three-dimensional array has three subscripts.

int cube[5, 13, 8];

Let's see a simple example of multidimensional array in C++ which declares, initializes and traverse two dimensional arrays.

#include <iostream>
using namespace std;
int main()
{
  int test[3][3];  //declaration of 2D array 
    test[0][0]=5;  //initialization 
    test[0][1]=10; 
    test[1][1]=15;
    test[1][2]=20;
    test[2][0]=30;
    test[2][2]=10;
    //traversal  
    for(int i = 0; i < 3; ++i)
    {
        for(int j = 0; j < 3; ++j)
        {
            cout<< test[i][j]<<" ";
        }
        cout<<"\n"; //new line at each row 
    }
    return 0;
}

Initializing Multidimensional Arrays

You can initialize multidimensional arrays with values just like single-dimension arrays. Values can either be filled in one at a time or all at once during the declaration.

Here’s an example:

int box[5][3] = { 8, 6, 7, 5, 3, 0, 9, 2, 1, 7, 8, 9, 0, 5, 2 };

The first value is assigned to box[0][0], the second to box[0][1], and the third to box [0][2]. The next value is assigned to box[1][0], then box[1][1] and box[1][2].

Let's see a simple example of multidimensional array which initializes array at the time of declaration.

#include <iostream>
using namespace std;
int main()
{
  int test[3][3] =
    {
        {2, 5, 5},
        {4, 0, 3},
        {9, 1, 8}  };  //declaration and initialization  
    //traversal  
    for(int i = 0; i < 3; ++i)
    {
        for(int j = 0; j < 3; ++j)
        {
            cout<< test[i][j]<<" ";
        }
        cout<<"\n"; //new line at each row 
    }
    return 0;
}

To have more clarity, you could group the initializations with braces, organizing each row on its own line.

int box[5][3] = {
{8, 6, 7},
{5, 3, 0},
{9, 2, 1},
{7, 8, 9},
{0, 5, 2} };

The compiler ignores the inner braces. This makes it easier to see how the numbers are distributed. Each value must be separated by a comma without regard to the braces. The entire initialization set must be within braces, and it must end with a semicolon.