Array with two-dimensions

August 13, 2023

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A two-dimensional array can be created using the traditional C-style array or with the C++ standard array container. Both approaches are demonstrated below.

Using a C-style array

A traditional C-style array can be used to create a 2D array. The array in this example has 3 rows and 4 columns with integer values.

int arr[3][4] = {{10, 11, 12, 13},
                 {14, 15, 16, 17},
                 {18, 19, 20, 21}};

for (int i = 0; i < 3; ++i) {
    for (int j = 0; j < 4; ++j) {
        std::cout << arr[i][j] << " ";
    }
    std::cout << std::endl;
}

The output from this example is shown below:

10 11 12 13
14 15 16 17
18 19 20 21

Using the standard array container

The std::array container can also be used to create a 2D array.

#include <iostream>
#include <array>

std::array<std::array<int, 4>, 3> arr = {{{10, 11, 12, 13},
                                          {14, 15, 16, 17},
                                          {18, 19, 20, 21}}};

for (int i = 0; i < 3; ++i) {
    for (int j = 0; j < 4; ++j) {
        std::cout << arr.at(i).at(j) << " ";
    }
    std::cout << std::endl;
}

This outputs the following:

10 11 12 13
14 15 16 17
18 19 20 21