How to make jagged array to 2D array C#

Question

I want to make 2D jagged array with different column lengths as 2D array with equal column lengths. I tried converting int[][] to List<List<int>>. For example, How do I make

int[][] = 
{0,1,1},
{1,1,1,1},
{1,1,1,1},
{0,1,1}

To

int[][] = 
{0,1,1,0},
{1,1,1,1},
{1,1,1,1},
{0,1,1,0}  // (inserting 0 to extended space)

Answer 1

You're using int[][] in both times, and not the alternative int[,] so I will ignore terminology and will assume you just want to pad 0's to make everything the same length:

int[][] arr = ...

int maxLength = arr.Max(x => x.Length);
var arr2 = arr.Select(x =>
                      {
                          if (x.Length == maxLength)
                              return x;
                          var y = new int[maxLength];
                          x.CopyTo(y, 0);
                          return y;
                      }).ToArray();

// now arr2 is the same as arr but with uniform lengths and padded 0's at the end

This approach performs many allocations. Another approach would be this:

List<List<int>> lists = ...

// with linq:
int maxLength = lists.Max(x => x.Count);

// without-linq:
int maxLength = 0;
foreach (var list in lists)
    if (list.Count > maxLength)
        maxLength = list.Count;
// end without-linq

foreach (List<int> list in lists)
    while (list.Count < maxLength)
        list.Add(0);

Choose the one you like better and better suits your situation.

You can avoid using Linq (if you want) in the first approach as well, but I didn't bother for that one.