CODEWITHSUNDEEP
c#arrayslistcollectionsienumerable
alan2here
alan2here

Reputation: 3317

Constructing C# Lists from that what is enumerable

var t = new List<byte?[,]>();
var t2 = new byte?[4, 4][];

var r = new List<byte?[,]>(t);
var r2 = new List<byte?[,]>(t2); // error

I thought C# lists and arrays are both Enumerable, and that lists can be constructed from an enumerable object to create a copy of the collection.

Whats wrong with the last line from the example above?

Compile error: The best overloaded method match for 'List.List(IEnumerable)' has some invalid arguments.

Upvotes: 4

Views: 203

Answers (2)

HatSoft
HatSoft

Reputation: 11201

Whats wrong with the last line from the example above?

The line throws error because t2 is new byte?[4, 4] a array of 2d array, well as r2 is a List of byte?[,] 2d array

var r2 = new List<byte?[,]>(t2); // error

so solution will be do pass a list of byte?[,] in it like this

var r2 = new List<byte?[,]>(new List<byte?[,]>());

Also t is the matching 2d array in a list that can be passed in r2

var r2 = new List<byte?[,]>(t);

Upvotes: 0

gwiazdorrr
gwiazdorrr

Reputation: 6329

If t2 should be an array of 2D arrays (list assignment suggests so) then the declaration of t2 is wrong. If think you are after:

var t = new List<int[,]>();
var t2 = new int[10][,];
for (int i = 0; i < t2.Length; ++i)
{
    t2[i] = new int[4, 4];
}

var r = new List<int[,]>(t);
var r2 = new List<int[,]>(t2); // no error!

Upvotes: 3

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