字符串搜索的Sunday算法

public class SUNDAY
    {
        public SUNDAY()
        {
          //
          // TODO: 在此处添加构造函数逻辑
          //
        }

        public int QfindChr(string str, string Sfind)
        {
            int str_length = 0;
            int fin_length = 0;

            int find_count = 0;
            int start = 0;
            int moveNum = 0;

            if (str.Length < Sfind.Length)
            {
                return find_count;
            }

            str_length = str.Length;
            fin_length = Sfind.Length;

            while (start + fin_length <= str_length)
            {
                moveNum++;
                bool isfind = false;//是否在这次移动中找到
                string s_temp = str.Substring(start, fin_length);
                if (s_temp == Sfind)
                { find_count++; start = start + fin_length; isfind = true; }
                if (isfind == false)//如果没找到计算下次移动位置
                {
                    int forwardPos = QfindPos(str, Sfind, start, fin_length);
                    start = forwardPos;
                }
            }
            return find_count;
        }

        //找字符在字符串(不算最后一个字符)的位置(倒数)
        //没找到返回fin_length,找到返回位置
        /**//// <summary>
        /// 找字符在字符串(不算最后一个字符)的位置(倒数);没找到返回str.length,找到返回位置
        /// </summary>
        /// <param name="str"></param>
        /// <param name="find"></param>
        /// <param name="pos"></param>
        /// <param name="fin_length"></param>
        /// <returns></returns>
        public int QfindPos(string str, string find, int pos, int fin_length)
        {
            int returnPos = str.Length;
            char[] Schr = str.ToCharArray();
            char[] Sfin = find.ToCharArray();
            if ((pos + fin_length) < str.Length)
            {
                char chrFind = Schr[pos + fin_length];//要找的字符
                if (fin_length >= 1)
                {
                    if (find.LastIndexOf(chrFind) > -1)
                    {
                        returnPos = pos + fin_length - find.LastIndexOf(chrFind);
                    }
                    else
                    {
                        returnPos = pos + fin_length + 1;
                    }
                }
            }
            return returnPos;
        }
}