compare strings containing numbers

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Text;

public class NumberStringComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        string[] xs = Split(x), ys = Split(y);
        int len = Math.Min(xs.Length, ys.Length);
        for (int i = 0; i < len; i++)
        {
            string xx = xs[i], yy = ys[i];
            if (xx.Length < yy.Length) return -1;
            if (xx.Length > yy.Length) return 1;
            int cmp = xx.CompareTo(yy);
            if (cmp != 0) return cmp;
        }
        if (xs.Length < ys.Length) return -1;
        if (xs.Length > ys.Length) return 1;
        return 0;
    }

    public static string[] Split(string s)
    {
        var ret = new List<string>();
        var num = new StringBuilder();
        foreach (char ch in s)
        {
            if ('0' <= ch && ch <= '9')
                num.Append(ch);
            else if ('０' <= ch && ch <= '９')
                num.Append((char)('0' + (ch - '０')));
            else
            {
                if (num.Length > 0)
                {
                    ret.Add(num.ToString());
                    num.Length = 0;
                }
                ret.Add(ch.ToString());
            }
        }
        if (num.Length > 0) ret.Add(num.ToString());
        return ret.ToArray();
    }
}