Two Dimensional Array in C++ | Basics of C++ - Software Development PDF Download

What is an Array?

An array is a collection of elements of the same data type, stored in contiguous memory locations. It provides a convenient way to store and access multiple values using a single variable.

What is a Two-Dimensional Array?

A two-dimensional array is an array in which elements are arranged in a two-dimensional grid or matrix. It can be visualized as a table with rows and columns. This data structure is useful when working with grids, matrices, tables, and other similar structures.

Declaring a Two-Dimensional Array

To declare a two-dimensional array in C++, you specify the data type of the elements and the dimensions of the array. The syntax for declaring a two-dimensional array is as follows:

dataType arrayName[rowSize][columnSize];

Here, 'dataType' is the type of elements in the array, 'arrayName' is the name of the array, 'rowSize' specifies the number of rows, and 'columnSize' specifies the number of columns.

Example: Declaring a Two-Dimensional Array

Let's declare a two-dimensional integer array named 'matrix' with 3 rows and 4 columns:

int matrix[3][4];

Accessing Elements in a Two-Dimensional Array

To access an element in a two-dimensional array, you use the row and column indices. The indices start from 0 and go up to the size of the array minus 1.

Example: Accessing Elements in a Two-Dimensional Array

int matrix[3][4];

// Assigning values to elements

matrix[0][0] = 1;

matrix[0][1] = 2;

matrix[0][2] = 3;

matrix[0][3] = 4;

matrix[1][0] = 5;

matrix[1][1] = 6;

matrix[1][2] = 7;

matrix[1][3] = 8;

matrix[2][0] = 9;

matrix[2][1] = 10;

matrix[2][2] = 11;

matrix[2][3] = 12;

// Accessing elements

cout << matrix[0][0];  // Output: 1

cout << matrix[1][2];  // Output: 7

Initializing a Two-Dimensional Array

You can initialize a two-dimensional array at the time of declaration using an initializer list. The number of elements in the initializer list should match the size of the array.

Example: Initializing a Two-Dimensional Array

int matrix[2][3] = {

    {1, 2, 3},

    {4, 5, 6}

};

Iterating Over a Two-Dimensional Array

You can use nested loops to iterate over the elements of a two-dimensional array. The outer loop controls the rows, and the inner loop controls the columns.

Example: Iterating Over a Two-Dimensional Array

int matrix[3][3] = {

    {1, 2, 3},

    {4, 5, 6},

    {7, 8, 9}

};

// Printing elements

for (int i = 0; i < 3; i++) {

    for (int j = 0; j < 3; j++) {

        cout << matrix[i][j] << " ";

    }

    cout << endl;

}

Output

1 2 3 

4 5 6 

7 8 9

Sample Problems

Problem 1: Write a C++ program to find the sum of all elements in a given 3x3 matrix.

#include <iostream>

using namespace std;

int main() {

    int matrix[3][3] = {

        {1, 2, 3},

        {4, 5, 6},

        {7, 8, 9}

    };

    

    int sum = 0;

    

    for (int i = 0; i < 3; i++) {

        for (int j = 0; j < 3; j++) {

            sum += matrix[i][j];

        }

    }

    

    cout << "Sum of elements: " << sum << endl;

    

    return 0;

}

Output

Sum of elements: 45

Problem 2: Write a C++ program to find the maximum element in a given 4x4 matrix.

#include <iostream>

using namespace std;

int main() {

    int matrix[4][4] = {

        {3, 7, 2, 9},

        {4, 1, 8, 5},

        {6, 2, 4, 7},

        {9, 3, 5, 1}

    };

    

    int maxElement = matrix[0][0];

    

    for (int i = 0; i < 4; i++) {

        for (int j = 0; j < 4; j++) {

            if (matrix[i][j] > maxElement) {

                maxElement = matrix[i][j];

            }

        }

    }

    

    cout << "Maximum element: " << maxElement << endl;

    

    return 0;

}

Output

Maximum element: 9

Conclusion

In this article, we covered the basics of two-dimensional arrays in C++. We learned how to declare, access, initialize, and iterate over two-dimensional arrays. Two-dimensional arrays are a powerful tool for handling structured data in programming. By understanding and practicing with them, you'll be well-equipped to work with grids, matrices, and tables in your C++ programs.