Is there a way to define a List<> of two elements string array?

Question

I want to build two-dimentional array of strings where length of one dimention is 2. Similar to this

string[,] array = new string[,]
{
    {"a", "b"},
    {"c", "d"},
    {"e", "f"},
    {"g", "h"}
}

Doing

List<string[]> list = new List<string[]>();

list.Add(new string[2] {"a", "b"});
list.Add(new string[2] {"c", "d"});
list.Add(new string[2] {"e", "f"});
list.Add(new string[2] {"g", "h"});

list.ToArray();

gives me

string[][]

but not

string[,] 

array.

Just curious, is there some trick to build dynamically

string[,] 

array somehow?

Answer 1

You can do this.

List<KeyValuePair<string, string>>

The idea being that the Key Value Pair would mimic the array of strings you replicated.

Answer 2

Well, you could reasonably easily write an extension method to do it. Something like this (only tested very slightly):

public static T[,] ToRectangularArray<T>(this IEnumerable<T[]> source)
{
    if (!source.Any())
    {
        return new T[0,0];
    }

    int width = source.First().Length;
    if (source.Any(array => array.Length != width))
    {
         throw new ArgumentException("All elements must have the same length");
    }

    T[,] ret = new T[source.Count(), width];
    int row = 0;
    foreach (T[] array in source)
    {
       for (int col=0; col < width; col++)
       {
           ret[row, col] = array[col];
       }
       row++;
    }
    return ret;
}

It's a slight shame that the above code uses T[] as the element type. Due to generic invariance I can't currently make source IEnumerable<IEnumerable<T>> which would be nice. An alternative might be to introduce a new type parameter with a constraint:

public static T[,] ToRectangularArray<T,U>(this IEnumerable<U> source)
    where U : IEnumerable<T>

Somewhat hairy, but it should work. (Obviously the implementation needs some changes too, but the basic principle is the same.)