C# 改良Substring

public static string SubString(string strData, int startIndex, int length) 
        {            int intLen = strData.Length;            int intSubLen = intLen - startIndex;            string strReturn; 

            if (length == 0)                strReturn = "";            else            {                if (intLen <= startIndex)                    strReturn = "";                else                {                    if (length > intSubLen)                        length = intSubLen;

                    strReturn = strData.Substring(startIndex, length);                }            }            return strReturn;        }

轉載 http://janema66.pixnet.net/blog/post/11569576-c%23-%E6%94%B9%E8%89%AFsubstring