Converting IList to List()

Question

I have a function that takes IList<string> someVariable as a parameter. I want to convert this to a list so I can sort the values alphabetically.

How do I achieve this?

Do you actually need to sort the list, or just iterate over it in a particular order? — Roman, Sep 01 '11 at 13:23

score 8 · Accepted Answer · answered Sep 01 '11 at 13:13

8

you can just do

var list = new List<string>(myIList);
list.Sort();

or

var list = myIList as List<string>;
if (list != null) list.Sort; // ...

answered Sep 01 '11 at 13:13

Random Dev

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Just because the given `IList` isn't specifically a `List`, doesn't mean you can't sort it. [`ReadOnlyCollection`](http://msdn.microsoft.com/en-us/library/ms132474.aspx) implements `IList` but isn't a `List`. You should still be able to make a copy of it and sort it. The second example you posted is wrong. – Roman Sep 01 '11 at 13:22
maybe I was not 100% clear in this - it's not wrong it's just not working in this kind of situations (Sort will just not be called) - but thank your for the hint - I guess there are enough examples here to pick one :) – Random Dev Sep 01 '11 at 13:33
How is *not working in this kind of situation* not wrong? The reason `IList` presumably **how** the given `IList` is implemented is an unimportant implementation detail that could change without warning. Your second example would silently start to fail. I'd say forcing an explicit dependency where there isn't one is **wrong**. – Roman Sep 01 '11 at 13:37
Your first example is exactly what I was after. Thanks – hoakey Sep 01 '11 at 14:07

score 7 · Answer 2 · answered Sep 01 '11 at 13:14

7

IList<string> someVariable = GetIList();
List<string> list = someVariable.OrderBy(x => x).ToList();

answered Sep 01 '11 at 13:14

Bala R

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John Kraft · Answer 3 · 2011-09-01T13:23:07.750

6

IList implements IEnumerable. Use the .ToList() method.

var newList = myIList.ToList();
newList.Sort();

edited Sep 01 '11 at 13:23

answered Sep 01 '11 at 13:14

John Kraft

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1

I think you need to call `.Cast<>` before `.ToList` – Sep 01 '11 at 13:18

score 2 · Answer 4 · answered Sep 01 '11 at 13:16

2

You can use linq to sort an IList<string> like so:

IList<string> foo = .... ; // something
var result = foo.OrderBy(x => x);

answered Sep 01 '11 at 13:16

recursive

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score 2 · Answer 5 · answered Sep 01 '11 at 13:18

You don't have to convert to a List to sort things. Does your sorting method require a List but not accept an IList. I would think this is the actual problem.

Furthermore if you really need a List, if your IList realy is a List (which is somewhat likely) you can just interpret it as such. So I would first check if it is already a List before creating a new one

var concreteList = parameter as List<T> ?? parameter.ToList();

Converting IList to List()

5 Answers5