C++ Multi-dimensional Arrays


C++ allows multidimensional arrays. Here is the general form of a multidimensional array declaration −

type name[size1][size2]...[sizeN];

For example, the following declaration creates a three dimensional 5 . 10 . 4 integer array −

int threedim[5][10][4];

Two-Dimensional Arrays

The simplest form of the multidimensional array is the two-dimensional array. A two-dimensional array is, in essence, a list of one-dimensional arrays. To declare a two-dimensional integer array of size x,y, you would write something as follows −

type arrayName [ x ][ y ];

Where type can be any valid C++ data type and arrayName will be a valid C++ identifier.

A two-dimensional array can be think as a table, which will have x number of rows and y number of columns. A 2-dimensional array a, which contains three rows and four columns can be shown as below −

Two Dimensional Arrays

Thus, every element in array a is identified by an element name of the form a[ i ][ j ], where a is the name of the array, and i and j are the subscripts that uniquely identify each element in a.

Initializing Two-Dimensional Arrays

Multidimensioned arrays may be initialized by specifying bracketed values for each row. Following is an array with 3 rows and each row have 4 columns.

int a[3][4] = {  
   {0, 1, 2, 3} ,   /*  initializers for row indexed by 0 */
   {4, 5, 6, 7} ,   /*  initializers for row indexed by 1 */
   {8, 9, 10, 11}   /*  initializers for row indexed by 2 */

The nested braces, which indicate the intended row, are optional. The following initialization is equivalent to previous example −

int a[3][4] = {0,1,2,3,4,5,6,7,8,9,10,11};

Accessing Two-Dimensional Array Elements

An element in 2-dimensional array is accessed by using the subscripts, i.e., row index and column index of the array. For example −

int val = a[2][3];

The above statement will take 4th element from the 3rd row of the array. You can verify it in the above digram.

#include <iostream>
using namespace std;
int main () {
   // an array with 5 rows and 2 columns.
   int a[5][2] = { {0,0}, {1,2}, {2,4}, {3,6},{4,8}};
   // output each array element's value                      
   for ( int i = 0; i < 5; i++ )
      for ( int j = 0; j < 2; j++ ) {
         cout << "a[" << i << "][" << j << "]: ";
         cout << a[i][j]<< endl;
   return 0;

When the above code is compiled and executed, it produces the following result −

a[0][0]: 0
a[0][1]: 0
a[1][0]: 1
a[1][1]: 2
a[2][0]: 2
a[2][1]: 4
a[3][0]: 3
a[3][1]: 6
a[4][0]: 4
a[4][1]: 8

As explained above, you can have arrays with any number of dimensions, although it is likely that most of the arrays you create will be of one or two dimensions.


Useful Video Courses


C++ Online Training

154 Lectures 11.5 hours

Arnab Chakraborty


Learn C++ Pointers with Visual Studio 2017

14 Lectures 57 mins

Kaushik Roy Chowdhury


Modern OpenGL C++ 3D Game & 3D Rendering

30 Lectures 12.5 hours

Frahaan Hussain


Cocos2d-x v3 C++ - Beginning Game Development

54 Lectures 3.5 hours

Frahaan Hussain


C++ Development - The Complete Coding Guide

77 Lectures 5.5 hours

Frahaan Hussain


Tic-Tac-Toe Clone - The Complete Cocos2d-x C++ Game Course

12 Lectures 3.5 hours

Frahaan Hussain