Question

Lets tell i’ve got 2D array of dictionaries:

public Dictionary<int, string>[,] mat = new Dictionary<int, string>[3, 5]
{
  { new Dictionary<int, string>(), new Dictionary<int, string>(), new Dictionary<int, string>() },
  { new Dictionary<int, string>(), new Dictionary<int, string>(), new Dictionary<int, string>() },
  { new Dictionary<int, string>(), new Dictionary<int, string>(), new Dictionary<int, string>() },
  { new Dictionary<int, string>(), new Dictionary<int, string>(), new Dictionary<int, string>() },           
  { new Dictionary<int, string>(), new Dictionary<int, string>(), new Dictionary<int, string>() }
}

And i need to copy this to another. I tried all ways.
Something like:

matNew = mat;

But still when i change the first one, ,it automatically change the second one.
I really don’t know how to do this.

Answer 1

I assume you want a deep copy?

var matNew = new Dictionary<int, string>[mat.GetLength(0), mat.GetLength(1)];
for (int i = 0; i < mat.GetLength(0); ++i)
    for (int j = 0; j < mat.GetLength(1); ++j)
        matNew[i, j] = new Dictionary<int, string>(mat[i, j]);

The Dictionary(IDictionary<TKey, TValue>) constructor copies all elements from the specified dictionary, and is probably the fastest way of performing a shallow clone of an existing dictionary. This is suitable for your case, since your keys and values are both immutable (int and string).