sorting

rvdenden

using System.Linq; public class record { public string name1; public string name2; } List records = new List(); records.Add(new record() { name1 = "a", name2 = "b" }); records.Add(new record() { name1 = "c", name2 = "d" }); records.Add(new record() { name1 = "e", name2 = "f" }); records.Add(new record() { name1 = "g", name2 = "h" }); records.Add(new record() { name1 = "i", name2 = "j" }); var r = records.OrderByDescending(sort => sort.name1).OrderBy(sort2 => sort2.name2);;

Nuri Ismail

There are lots of ways of sorting the list: see here[^]. :) I would suggest you implement the IComparable<T>[^] interface and provide an appropriate body for CompareTo method. You can find such an example here[^].

Ramkithepower wrote:

Now I have to sort this class first by name1 and then by name2.

In this case a possible implementation of the CompareTo method could be:

public int CompareTo(Record other)
{
int res = name1.CompareTo(other.name1);

if(res == 0)
res = name2.CompareTo(other.name2);

return res;
}

Simon P Stevens

You can use OrderBy[^]

var sortedData = records.OrderBy(r => r.name1 + r.name2);

You just concatenate the names in the key selector to achieve the ordering you want. Opps. PIEBALDconsult[^] is of course totally right. That was a very stupid suggestion of mine, I don't know what I was thinking. Please ignore the above suggestion. This is how you should really do it (using ThenBy[^]):

var sortedData = records.OrderBy(sort => sort.name1).ThenBy(sort2 => sort2.name2);

Simon

PIEBALDconsult

I don't think that's reliable.

Simon P Stevens

rvdenden wrote:

var r = records.OrderByDescending(sort => sort.name1).OrderBy(sort2 => sort2.name2);;

This isn't correct.

MSDN - OrderBy[^]:

Because IOrderedEnumerable inherits from IEnumerable, you can call OrderBy or OrderByDescending on the results of a call to OrderBy, OrderByDescending, ThenBy or ThenByDescending. Doing this introduces a new primary ordering that ignores the previously established ordering.

You need to use ThenBy[^] for the second stage of the sort.

var r = records.OrderByDescending(sort => sort.name1).ThenBy(sort2 => sort2.name2);

Simon

Simon P Stevens

Why?

Simon

Luc Pattyn

This article[^] covers the regular ways of sorting; it should be easy to understand and offer good performance at the same time; it does not offer the latest LINQ fancy things. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

PIEBALDconsult

Unless you right-pad name1. Or are you counting on case-sensitivity?

Lost User

Suppose name1 is the empty string..? edit: ok you changed it

modified on Thursday, May 27, 2010 9:47 AM

Simon P Stevens

Ohh... You are very right. Thanks. Will edit.

Simon

Luc Pattyn

because it is wrong. consider the following set of string pairs:

a,bd
ab,c

and try sorting them the right way and the concatenated way. It would be right if you were to use string1 + charMax + string2 where charMax is a character that sorts last in the character collection. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

Ramkithepower

Thank you all for the reply.

Jack Sparrow -------------------------------------- Defeat is not the worst of failures. Not to have tried is the true failure.