What are the differences between using int[][] and int[,]? [duplicate]

Answer 1

The best way to understand the difference is to look at two ways to create an nxn matrix:

const int n = 8, m = 8;

int[,] matrix1 = new int[n,m];

int[][] matrix2 = new int[n][];
for (int i = 0; i < matrix2.Length; i++) { matrix2[i] = new int[m]; }

matrix1[1,1] = matrix2[2][2];

As you can see the second one is a bit more involved because you need the for-loop to fully create it. It is often called a jagged array because the 2nd order arrays do not need to be all of the same length.