declare matrix in c++ code example

Example 1: create matrix cpp

typedef std::vector<std::vector<double> > Matrix;
//with initialization
Matrix matrix1 = { {0.1,1.1,.2},
                 {.4,.5,.6}, 
                 {.8,.9,.10}
                };
//just initiation (3x3)
Matrix matrix2(3, std::vector<double>(3) );

Example 2: 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 }