Sorting lambda expression for this

Question

I have a list of items which I want to sort but I can't seems to get the lambda expression right. can someone leads me to the lambda expression? Thanks

unsorted list item:

number: 2, Date: 21/10/2010 11:22:55
number: 1, Date: 21/10/2010 11:22:55
number: 2, Date: 20/10/2010 12:10:00
number: 1, Date: 20/10/2010 12:10:00

sorted list item:

number: 1, Date: 21/10/2010 11:22:55
number: 1, Date: 20/10/2010 12:10:00
number: 2, Date: 21/10/2010 11:22:55
number: 2, Date: 20/10/2010 12:10:00

itemList.sort((x, y) => ...);

score 4 · Accepted Answer · answered Jul 15 '13 at 05:31

4

You can use Linq's OrderBy and ThenByDescending extension methods:

using System.Linq;
...

var sortedItems = 
    itemList.OrderBy(x => x.number)
            .ThenByDescending(x => x.Date);

This will create a new object. If you want to assign it back to the original itemList, simply do this:

using System.Linq;
...

itemList = itemList.OrderBy(x => x.number)
                   .ThenByDescending(x => x.Date)
                   .ToList();

answered Jul 15 '13 at 05:31

p.s.w.g

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i forgot to state that the itemList datatype is List. there is no orderby method in native c# list – user1599647 Jul 15 '13 at 05:34
2

Well no.. that's what the `System.Linq` namespace is for.. – Simon Whitehead Jul 15 '13 at 05:34
There is.. You probably need using System.Linq; as all Linq is implemented as extension methods on IEnumerable – cwap Jul 15 '13 at 05:36
oh I forgot to add linq namespace – user1599647 Jul 15 '13 at 05:39
@user1599647, it's an extension method. – Sam Jul 15 '13 at 05:41

Sorting lambda expression for this

1 Answers1