SemiNumericComparer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Comparer
{
    public class SemiNumericComparer : IComparer<string>
    {
        public int Compare(string s1, string s2)
        {
            int res = Compare(s1, s2, true);
            return res;
        }
        public int Compare(string s1, string s2, bool toplevel)
        {
            int localRes = 0;
            //Purely Numeric Comparisons
            if (IsNumeric(s1) && IsNumeric(s2))
            {
                if (Convert.ToInt32(s1) > Convert.ToInt32(s2)) return 1;
                if (Convert.ToInt32(s1) < Convert.ToInt32(s2)) return -1;
                if (Convert.ToInt32(s1) == Convert.ToInt32(s2)) return 0;
            }

            string[] split1 = s1.Split(' ');
            string[] split2 = s2.Split(' ');
            //If we're dealing with words...might need to recursively call
            if (split1.Length > 1 || split2.Length > 1)
            {
                if (split1.Length == 1) //only one of these has words, and it must be split2
                {
                    localRes = Compare(s1, split2[0], false);//check s1 against the first word in s2
                    if (localRes == 0) { return -1; }//If the single word == the first word in the other..then the single wins
                    else return localRes;

                }
                if (split2.Length == 1) //only one of these has words, and it must be split1 
                {
                    localRes = Compare(split1[0], s2, false);//check s2 against the first word in s1
                    if (localRes == 0) { return 1; }
                    else return localRes;
                }

                //If the first word is the same..lets compare the rest
                if (split1[0] == split2[0])
                {
                    List<string> l1 = new List<string>(split1);
                    l1.RemoveAt(0);
                    List<string> l2 = new List<string>(split2);
                    l2.RemoveAt(0);

                    return Compare(String.Join(" ", l1), string.Join(" ", l2), false);
                }

            }


            if (IsNumeric(s1) && !IsNumeric(s2))
                return -1;

            if (!IsNumeric(s1) && IsNumeric(s2))
                return 1;

            return string.Compare(s1, s2, true);
        }

        public static bool IsNumeric(object value)
        {
            try
            {
                int i = Convert.ToInt32(value.ToString());
                return true;
            }
            catch (FormatException)
            {
                return false;
            }
        }
    }
}