Natural numeric sort in C#

问题

I have a problem when sorting a generic list in C#

I have a List<MyObjects> myList, and MyObject has a string property.

Now it looks like this when sorting descending

2.4.88

2.4.70

2.4.164 -> this is wrong

2.4.15

How do I sort my list?

I have tried:

myList.sort(delegate(MyObjects obj1, MyObjects obj2)
{
    return obj2.version.CompareTo(obj1.version);
});

Its not an option to use Linq (older framework)

UPDATE: My list can also contains N/A

回答1:

You cannot compare as strings, because obviously thats the proper string sorting. You need to parse to numbers or to an instance of the Version class:

myList.sort(delegate(MyObjects obj1, MyObjects obj2)
{
    return new Version(obj2.version).CompareTo(new Version(obj1.version));
});

回答2:

I had to do natural sorting a while ago. Don't remember where I found the code, but stuck it on my blog for future reference: http://www.geekality.net/2009/03/02/natural-sorting

Here's the code:

using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Security;

namespace NaturalSort
{
     public sealed class NaturalStringComparer : IComparer<string>
     {
         private readonly int modifier = 1;

         public NaturalStringComparer(bool descending)
         {
             if (descending)
                 modifier = -1;
         }

         public NaturalStringComparer()
             :this(false) {}

         public int Compare(string a, string b)
         {
             return SafeNativeMethods.StrCmpLogicalW(a ?? "", b ?? "") * modifier;
         }
     }

     public sealed class NaturalFileInfoComparer : IComparer<FileInfo>
     {
         public int Compare(FileInfo a, FileInfo b)
         {
             return SafeNativeMethods.StrCmpLogicalW(a.Name ?? "", b.Name ?? "");
         }
     }

     [SuppressUnmanagedCodeSecurity]
     internal static class SafeNativeMethods
     {
         [DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
         public static extern int StrCmpLogicalW(string psz1, string psz2);
     }
}

You'd use it along these lines:

myList.Sort(new NaturalStringComparer(true));

回答3:

Perhaps sort via Version?

return (Version.Parse(obj2.version)).CompareTo(Version.Parse(obj1.version));

of course, it will be cheaper if you do the parsing once and once only (maybe make version a Version instead of a string)

回答4:

If your string pattern fits the .Net version class then convert it to a Version object and compare.

回答5:

Maybe one on these may help you:

Natural Sorting in C#
The Alphanum Algorithm

回答6:

Can you describe how it is wrong. Looks like it is perfectly placed in order. However, just a random suggestion, if you are sure of format you can break the string and convert to number to check this kind of stuff.

来源：https://stackoverflow.com/questions/9430674/natural-numeric-sort-in-c-sharp

标签

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