CODEWITHSUNDEEP
c#.netlistcollections
Mykhailo Vashchuk
Mykhailo Vashchuk

Reputation: 123

Convert List<int>to List<List<int>>

Can i convert List<int>to List<List<int>> in c#? When I use such construction 

List<int>element=new List<int>();
List<List<int>>superElement= new List<List<int>>(element);

I get a fault,but can I do this in another way?

Upvotes: 5

Views: 613

Answers (6)

musefan
musefan

Reputation: 48415

Due to the fact I do not believe the other answers have really put in much effort to help, I am going to post what I believe to be a more complete and useful answer.

To start with, and for completeness I will show how to achieve what was actually trying to be done. To create a List of Lists you can do this:

List<int> element = new List<int>();
List<List<int>> superElement = new List<List<int>>();
superElement.Add(element);

But as it stands, it doesn't make a lot of sense why you would want to do this, and after some comment probing (hope it didn't hurt) we have discovered that you want to pair up an ID with a List of integers. I would suggest taking a different approach to this.

Personally, I would create a class to hold my data, and then create a single List for those items, like so:

public class MyData
{
    public int ID {get; set;}
    public List<int> MyValues {get;set;}

    public MyData()
    {
        MyValues = new List<int>();
    }
}

Then you can do this:

List<int> element = new List<int>();
MyData data = new MyData();
data.ID = 1;
data.MyValues = element;

List<MyData> superElement = new List<MyData>();
superElement.Add(data);

Which would allow querying like so:

MyData data1 = superElement.SingleOrDeafult(x => x.ID == 1);
List<int> element = data1.MyValues;

Assuming you have Linq available.

An alternate method could be to use a dictionary, like so:

Dictionary<int, List<int>> superElement = new Dictionary<int, List<int>>();
superElement.Add(1, element);

where 1 is an ID, which you can call like so:

List<int> element = superElement[1];

Upvotes: 3

Darren
Darren

Reputation: 70718

Yes. You can use the collection initializer

List<int> element = new List<int>();
List<List<int>> superElement = new List<List<int>> { element };

http://msdn.microsoft.com/en-gb/library/vstudio/bb384062.aspx

Upvotes: 5

Joel in G&#246;
Joel in G&#246;

Reputation: 7570

If you just want to initialize the List, then 

List<List<int>>superElement= new List<List<int>>();

works; if you want it to contain one (empty) element initially then 

List<List<int>>superElement= new List<List<int>>{element};

will do it.

Upvotes: 4

Nolonar
Nolonar

Reputation: 6122

You can do it like this:

List<List<int>> superElement = new List<List<int>>();
superElement.Add(element);

Upvotes: 12

Cyril Gandon
Cyril Gandon

Reputation: 17048

Try this :

var element = new List<int>();
var superElement = new List< List<int> >(){ element };

Upvotes: 7

Po-ta-toe
Po-ta-toe

Reputation: 732

List<int>element=new List<int>();
List<List<int>>superElement= new List<List<int>> { element };

That'll work. You can't pass the list in the constructor.

Upvotes: 8

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