using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main()

    {

        var tagObjs = new List<TagObj>(new[]

                                       {

                                           new TagObj("A29"),

                                           new TagObj("A21"),

                                           new TagObj("A52"),

                                           new TagObj("A16"),

                                           new TagObj("A6")

                                       });

        Console.WriteLine("Before:");

        tagObjs.ForEach(t => Console.WriteLine("\t" + t.Tag));

​

        tagObjs.Sort(new TagObjComparer());

        Console.WriteLine("\n\nAfter:");

        tagObjs.ForEach(t => Console.WriteLine("\t" + t.Tag));

    }

}

​

public class TagObj

{

    public string Tag

    {

        get;

        set;

    }

​

    public TagObj(string tag)

    {

        Tag = tag;

    }

​

    public override string ToString()

    {

        return Tag;

    }

}

​

public class TagObjComparer : IComparer<TagObj>

{

    public int Compare(TagObj x, TagObj y)

    {

        return GetValue(x.Tag).CompareTo(GetValue(y.Tag));

    }

​

    private int GetValue(string str)

    {

        if (string.IsNullOrEmpty(str))

            return int.MaxValue;

        if (!char.IsLetter(str[0]))

            return int.MaxValue;

        int basenum = char.ToUpper(str[0]) - 'A' * 10000;

        int result;

        if (!int.TryParse(str.Substring(1), out result))

            return int.MaxValue;

        return basenum + result;

    }

}