How can I convert a list<> to a multi-dimensional array?

Question

I have the following method signature:

public void MyFunction(Object[,] obj)

I create this object:

List&         


        

Answer 1

Here is a solution using Linq's Aggregate extension.

Note that the below does not check, nor is concerned if it gets a jagged sub list, it uses the max size of all the sublists and fills in according to the current list. If that is a concern one could add a check to the if to check for the same count amongst all the sub lists.

public static T[,] To2DArray(this List> lst)
{

    if ((lst == null) || (lst.Any (subList => subList.Any() == false)))
        throw new ArgumentException("Input list is not properly formatted with valid data");

    int index = 0;
    int subindex;

    return 

       lst.Aggregate(new T[lst.Count(), lst.Max (sub => sub.Count())],
                     (array, subList) => 
                        { 
                           subindex = 0;
                           subList.ForEach(itm => array[index, subindex++] = itm);
                           ++index;
                           return array;
                         } );
}

Test / Usage

var lst = new List>() { new List() { "Alpha", "Beta", "Gamma" },
                                     new List() { "One", "Two", "Three" },
                                     new List() { "A" }
                                 };
var newArray = lst.To2DArray();

Result: