2d matrix cpp code example

Example 1: 2d array c++

int a[2][3]= {
        {1, 2, 3},
        {4, 5, 6}
    };
    
    cout << a[1][1]; // Output is 5

Example 2: c++ 2D vectors

int main() 
{ 
    int row = 5; // size of row 
    int colom[] = { 5, 3, 4, 2, 1 }; 
  
    vector<vector<int> > vec(row);  // Create a vector of vector with size equal to row. 
  	for (int i = 0; i < row; i++) { 
  		int col;  
        col = colom[i]; 
  		vec[i] = vector<int>(col); //Assigning the coloumn size of vector
        for (int j = 0; j < col; j++) 
            vec[i][j] = j + 1; 
    } 
  
    for (int i = 0; i < row; i++) { 
        for (int j = 0; j < vec[i].size(); j++) 
            cout << vec[i][j] << " "; 
        cout << endl; 
    } 
}

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;
}