How to order by descending versions list in c#?

Question

I'm having a list which has some versions in it .

sample data :

"4.5","2.1","2.2.1","7.5","7.5.3","N/A","2.3.4.5"

As you can see the data , i'm trying to sort list by Descending tough 3.8.5 is invalidnumber & NA is a invalid one .

Code :

decimal result;
var sortedVData = vData.OrderByDescending(v => decimal.TryParse(v.vCode, out result) ? Convert.ToDecimal(v.vCode) : decimal.MaxValue);

Output : "NA" , "7.5.3" , '2.3.4.5' , "2.2.1" , '7.5' , '4.5' , '2.1'

As you see in my else(:) condition i'm doing decimal.MaxValue to make NA to come top if there is invalid value (any string with text) but 2.2.1 should be a exception and should work as number(tough 2.2.1 or any number having multiple decimals a is invalid in version's point of view i want them made conditionally valid .

Expected Result : "NA" , "7.5.3" , "7.5" , "4.5" ,"2.3.4.5" ,"2.2.1" , "2.1"

Maybe use [`Version.TryParse`](https://msdn.microsoft.com/en-us/library/system.version.tryparse%28v=vs.110%29.aspx)? — Wai Ha Lee, Jan 05 '16 at 10:31
Are you looking for [Natural Sort Order](http://stackoverflow.com/questions/248603/natural-sort-order-in-c-sharp)? — Steve, Jan 05 '16 at 10:32
@WaiHaLee `version` i never knew it . let me give it a try . — super cool, Jan 05 '16 at 10:34
@mybirthname its a versioning convention tough i mentioned in my post its a invalid value . — super cool, Jan 05 '16 at 10:35
@mybirthname - It won't be any better than the answer [Tim Schmelter](http://stackoverflow.com/users/284240/tim-schmelter) posted. — Wai Ha Lee, Jan 05 '16 at 10:46

score 7 · Accepted Answer · edited May 23 '17 at 12:23

7

You can use Version.TryParse and this extension method for LINQ queries:

public static Version TryGetVersion(this string item)
{
    Version ver;
    bool success = Version.TryParse(item, out ver);
    if (success) return ver;
    return null;
}

Then the complete query is simple:

var sortedVData = vData
    .Select(v => new { Obj = v, Version = v.vCode.TryGetVersion() })
    .OrderBy(x => x.Version != null)    // first all invalid versions
    .ThenByDescending(x => x.Version)   // then by version descending
    .Select(x => x.Obj);

So actually it would be better to store versions instead of strings in your class.

It's better to use this extension in LINQ queries than using a local variable.

edited May 23 '17 at 12:23

Community

1
1

answered Jan 05 '16 at 10:36

Tim Schmelter

450,073
74
686
939

@waiHaLee comment helped me to frame what i need & your answer was absolutely spot on & clean . – super cool Jan 05 '16 at 11:21
`v.vCode.TryGetVersion()` will return null when i have `NA` in the list & end list will have null instead of `NA` on top – super cool Jan 05 '16 at 12:04
@supercool: No, i have used `.OrderBy(x => x.Version != null)` which moves the invalid versions to the top. You could also use `.OrderByDescending(x => x.Version == null)` or `.OrderBy(x => x.Version == null ? 0 : 1)`. The trick is that a comparison returns `true` or `false` and `true` has a higher value than `false`. That's why `.OrderBy(x => x.Version != null)` moves the valid versions to the bottom. You need `OrderBy` **and** `ThenByDescending` as shown above. – Tim Schmelter Jan 05 '16 at 12:08
humm yes i got the ordering part, its clever . when i tried using the same logic in my real code (i'm binding to dropdown , each list item has many entities i.e version etc not given in the sample ) there seem to be a slightest of issue . anyway i'll workaround it . cheers mate – super cool Jan 05 '16 at 12:19

score 1 · Answer 2 · answered Jan 05 '16 at 10:37

1

Like @WaiHaLee says, you can use Version, and it implements IComparable, so you can just do this:

static void Main(string[] args)
    {
        var data = new[] {"4.5","2.1","2.2.1","7.5","7.5.3",@"N/A","2.3.4.5"};
        foreach(var v in data.OrderByDescending(OrderVersion))
            Console.WriteLine(v);
    }

    private static IComparable OrderVersion(string arg)
    {
        //Treat N/A as highest version
        if (arg == "N/A")
            return new Version(Int32.MaxValue,Int32.MaxValue); 
        return Version.Parse(arg);
    }

answered Jan 05 '16 at 10:37

Mikael Nitell

1,069
6
16

This will fail for "11.1.2". I failed to read correctly – Wai Ha Lee Jan 05 '16 at 10:37
appreciate your time . ty – super cool Jan 05 '16 at 11:24

score 1 · Answer 3 · answered Jan 05 '16 at 10:47

public class VersionsComparer: IComparer<string>
{
    public int Compare(string x, string y)
    {

        if (x.ToLower() == @"n/a")
        {
            if (y.ToLower() == @"n/a")
                return 0;

            return -1;
        }

        if (y.ToLower() == @"n/a")
        {
            if (x.ToLower() == @"n/a")
                return 0;

            return 1;
        }

        var verX = Version.Parse(x);
        var verY = Version.Parse(y);

        return verX.CompareTo(verY);
    }
}

class Program
{
    static void Main(string[] args)
    {
        var versions = new[] { "4.5", "2.1", "2.2.1", "7.5", "7.5.3", @"N/A", "2.3.4.5" };


        foreach (var v in versions.OrderByDescending(v => v, new VersionsComparer()))
        {
            Console.WriteLine(v);
        }
    }


}

appreciate your time . ty – super cool Jan 05 '16 at 11:24 — super cool, Jan 05 '16 at 11:24

How to order by descending versions list in c#?

3 Answers3