C++ Multidimensional Arrays – 2D Arrays (With Examples)

Introduction

In this tutorial, we will learn about multidimensional arrays in C++, with a focus on 2D arrays (two-dimensional arrays).

A multidimensional array is essentially an array of arrays. Among them, 2D arrays are the simplest and most commonly used. They are often used to represent data in a tabular format (rows and columns) — just like a matrix.

👉 If you are new to arrays, you may first check out our guide on C++ Arrays before continuing.

General Declaration Syntax

The syntax for declaring a multidimensional array is:

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

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

Example of a 3D array declaration:

int threeD[5][10][4];

int threeD[5][10][4];

Two-Dimensional Arrays (2D Arrays)

A 2D array in C++ can be visualized as a table with rows and columns.
Each element of the array can be accessed using two indices:

• i → row index
• j → column index

Syntax:

type arrayName[rows][columns];

type arrayName[rows][columns];

For example:

int matrix[3][3];

int matrix[3][3];

This creates a 3×3 table (3 rows and 3 columns).

Declaring and Initializing 2D Arrays

There are multiple ways to initialize 2D arrays in C++:

Method 1: Row-by-Row Initialization

int Arr[3][3] = {
   {0, 1, 2},   // row 0
   {4, 5, 6},   // row 1
   {8, 9, 10}   // row 2
};

int Arr[3][3] = {
   {0, 1, 2},   // row 0
   {4, 5, 6},   // row 1
   {8, 9, 10}   // row 2
};

Method 2: Inline Initialization

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

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

Method 3: Single Element Assignment

int Arr[3][3];
Arr[0][1] = 50; // Sets element at row 0, column 1 to 50

int Arr[3][3];
Arr[0][1] = 50; // Sets element at row 0, column 1 to 50

Accessing 2D Array Elements

You can access elements using their row and column indices:

int x = Arr[0][1]; // Access element at row 0, column 1

int x = Arr[0][1]; // Access element at row 0, column 1

Traversing the Entire 2D Array

We generally use nested for loops:

for (int i = 0; i < rows; i++) {
    for (int j = 0; j < columns; j++) {
        cout << Arr[i][j] << " ";
    }
    cout << endl;
}

for (int i = 0; i < rows; i++) {
    for (int j = 0; j < columns; j++) {
        cout << Arr[i][j] << " ";
    }
    cout << endl;
}

Example Program: Input and Output of a 2D Array

#include <iostream>
using namespace std;

int main() {
    int A[2][2];

    // Taking input from the user
    cout << "Enter values of 2-D array A: " << endl;
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            cin >> A[i][j];
        }
    }

    // Printing the array
    cout << "Values of 2-D array A: " << endl;
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            cout << A[i][j] << " ";
        }
        cout << endl;
    }

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int A[2][2];

    // Taking input from the user
    cout << "Enter values of 2-D array A: " << endl;
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            cin >> A[i][j];
        }
    }

    // Printing the array
    cout << "Values of 2-D array A: " << endl;
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            cout << A[i][j] << " ";
        }
        cout << endl;
    }

    return 0;
}

Sample Input:

1 2
3 4

1 2
3 4

Sample Output:

Values of 2-D array A:
1 2
3 4

Values of 2-D array A:
1 2
3 4

Visual Representation of a 2D Array

Imagine this 2D array:

int A[2][2] = { {1, 2}, {3, 4} };

int A[2][2] = { {1, 2}, {3, 4} };

It looks like this:

👉 Each element is accessed as A[row][column].

Applications of 2D Arrays

2D arrays are widely used in:

• Matrices and mathematical computations
• Game boards (like Chess, Sudoku, Tic-Tac-Toe)
• Image processing (pixels stored in rows and columns)
• Tabular data storage (like student marks, sales data, etc.)

Key Takeaways

• A 2D array is like a table with rows and columns.
• Elements are accessed with two indices → Arr[i][j].
• You can initialize 2D arrays in multiple ways.
• Nested loops are commonly used to traverse 2D arrays.