C# Regex sorting letter and number strings

Question

I have a list that needs ordering say:

R1-1
R1-11
R2-2
R1-2

this needs to be ordered:

R1-1
R1-2
R1-11
R2-2

Currently I am using the C# Regex.Replace method and adding a 0 before the occurance of single numbers at the end of a string with something like:

Regex.Replace(inString,@"([1-9]$)", @"0$2")

I'm sure there is a nicer way to do this which I just can't figure out. Does anyone have a nice way of sorting letter and number strings with regex?

I have used Greg's method below to complete this and just thought I should add the code I am using for completeness:

public static List<Rack> GetRacks(Guid aisleGUID)
    {
        log.Debug("Getting Racks with aisleId " + aisleGUID);
        List<Rack> result = dataContext.Racks.Where(
                               r => r.aisleGUID == aisleGUID).ToList();
        return result.OrderBy(r => r.rackName, new NaturalStringComparer()).ToList();
    }

Greg Beech · Accepted Answer · 2010-01-23 11:15:55Z

4

I think what you're after is natural sort order, like Windows Explorer does? If so then I wrote a blog entry a while back showing how you can achieve this in a few lines of C#.

Note: I just checked and using the NaturalStringComparer in the linked entry does return the order you are looking for with the example strings.

edited Jan 23, 2010 at 11:15

answered Mar 25, 2009 at 8:39

Greg Beech

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4 Comments

bobwah Over a year ago

Great answer Greg! I have now used this solution and will add the method i am using in my question for completeness.

SpoiledTechie.com Over a year ago

Ya, great greg! Too bad the LINK is DEAD

Greg Beech Over a year ago

@Scott - sorry about that. I simplified the links on my blog and some of the redirects don't seem to be working properly. I've edited the post to have the updated link as well.

Pang Jan 22 at 8:17

Link in answer is dead - "404 Not Found".

chiccodoro · Accepted Answer · 2009-03-25 08:48:39Z

2

You can write your own comparator and use regular expressions to compare the number between "R" and "-" first, followed by the number after "-", if the first numbers are equal.

Sketch:

public int Compare(string x, string y)
{
    int releaseX = ...;
    int releaseY = ...;
    int revisionX = ...;
    int revisionY = ...;

    if (releaseX == releaseY)
    {
        return revisionX - revisionY;
    }
    else
    {
        return releaseX - releaseY;
    }
}

answered Mar 25, 2009 at 8:48

chiccodoro

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2 Comments

chiccodoro Over a year ago

Edit: Hmm.. Greg Beech's solution is nice! -- So take this as a way to solve it if you want to avoid the use of a DllImport.

bobwah Over a year ago

Thanks for the response! I have used Greg's solution but nice to have this for others reference.

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