2d array c 2b 2b

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

1int** arr = new int*[10]; // Number of Students
2int i=0, j;
3for (i; i<10; i++) 
4	arr[i] = new int[5]; // Number of Courses
5/*In line[1], you're creating an array which can store the addresses
6  of 10 arrays. In line[4], you're allocating memories for the 
7  array addresses you've stored in the array 'arr'. So it comes out 
8  to be a 10 x 5 array. */

1#include <iostream>
2using namespace std;
3int main(){
4	int n,m;
5	int a[n][m];
6	cin >> n >>m;
7	for ( int i=0; i<n; i++){
8		for (int j=0; j<m; j++){
9			cin >> a[i][j];
10		}
11	}
12	
13	for ( int x=0; x<n; x++){
14		for (int y=0; y<m; y++){
15			cout << "a[" << x << "][" << y << "]: ";
16			cout << a[x][y] << endl;
17		}
18	}
19	return 0;
20}

1
2int main() 
3{ 
4    int row = 5; // size of row 
5    int colom[] = { 5, 3, 4, 2, 1 }; 
6  
7    vector<vector<int> > vec(row);  // Create a vector of vector with size equal to row. 
8  	for (int i = 0; i < row; i++) { 
9  		int col;  
10        col = colom[i]; 
11  		vec[i] = vector<int>(col); //Assigning the coloumn size of vector
12        for (int j = 0; j < col; j++) 
13            vec[i][j] = j + 1; 
14    } 
15  
16    for (int i = 0; i < row; i++) { 
17        for (int j = 0; j < vec[i].size(); j++) 
18            cout << vec[i][j] << " "; 
19        cout << endl; 
20    } 
21} 

1#include <array>
22 #include <iostream>
33
44 using namespace std;
55
66 //remember const!
77 const int ROWS = 2;
88 const int COLS = 3;
99
1010 void printMatrix(array<array<int, COLS>, ROWS> matrix){
1111 //for each row
1212 for (int row = 0; row < matrix.size(); ++row){
1313 //for each element in the current row
1414 for (int col = 0; col < matrix[row].size(); ++col){
1515 cout << matrix[row][col] << ' ';
1616 }
1717 cout << endl;
1818 }
1919 }

1void printMatrix(array<array<int, COLS>, ROWS> matrix){
2for (auto row : matrix){
3//auto infers that row is of type array<int, COLS>
4for (auto element : row){
5cout << element << ' ';
6}
7cout << endl;
8}