c++ declare 2d array code example

Example 1: declaring 2d dynamic array c++

int** arr = new int*[10]; // Number of Students
int i=0, j;
for (i; i<10; i++) 
	arr[i] = new int[5]; // Number of Courses
/*In line[1], you're creating an array which can store the addresses
  of 10 arrays. In line[4], you're allocating memories for the 
  array addresses you've stored in the array 'arr'. So it comes out 
  to be a 10 x 5 array. */

Example 2: c++ code to write 2d array

#include <iostream>
using namespace std;
int main(){
	int n,m;
	int a[n][m];
	cin >> n >>m;
	for ( int i=0; i<n; i++){
		for (int j=0; j<m; j++){
			cin >> a[i][j];
		}
	}
	
	for ( int x=0; x<n; x++){
		for (int y=0; y<m; y++){
			cout << "a[" << x << "][" << y << "]: ";
			cout << a[x][y] << endl;
		}
	}
	return 0;
}

Example 3: get elements of 2d array c++

#include <array>
2 #include <iostream>
3
4 using namespace std;
5
6 //remember const!
7 const int ROWS = 2;
8 const int COLS = 3;
9
10 void printMatrix(array<array<int, COLS>, ROWS> matrix){
11 //for each row
12 for (int row = 0; row < matrix.size(); ++row){
13 //for each element in the current row
14 for (int col = 0; col < matrix[row].size(); ++col){
15 cout << matrix[row][col] << ' ';
16 }
17 cout << endl;
18 }
19 }

Example 4: get elements of 2d array c++

void printMatrix(array<array<int, COLS>, ROWS> matrix){
for (auto row : matrix){
//auto infers that row is of type array<int, COLS>
for (auto element : row){
cout << element << ' ';
}
cout << endl;
}