Copy a 2-dimensional array (matrix) in C++

This post will discuss copying a 2-dimensional array (i.e., matrix) in C++.

1. Using `std::copy`

The recommended solution to create a copy of a 2-dimensional array in C++ is using the std::copy function from C++ standard library. It is defined in the <algorithm> header. The following code example demonstrates the invocation of this function:

#include <iostream>

#include <algorithm>

#include <iomanip>

template<typename T, size_t N, size_t M>

void printMatrix(T(&mat)[N][M])

{

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

for (int j = 0; j < M; j++ ) {

std::cout << std::setw(2) << mat[i][j] << ' ';

}

std::cout << std::endl;

}

int main()

{

const int m = 3, n = 3;

int mat[m][n] = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

int copy[m][n];

std::copy(&mat[0][0], &mat[0][0] + m * n, &copy[0][0]);

printMatrix(copy);

return 0;

}

Download Run Code

Output:

1  2  3
4  5  6
7  8  9

2. Using for loop

Another option is to iterate over each row and column of the matrix using a regular for-loop and copy each element to its correct position in the destination array. This can be implemented as follows in C++.