C# 改良Substring－貞愛講

語言：C#
功能：string.Substring(startIndex, length)改良
原因：當StartIndex + length > string.Length時會發生錯誤，但程式執行時有時不知道字長度，造成錯誤，很麻煩，只好自己改良了
語法：

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;
        }

範例：

string strReturn = "";
string strData = "0123456789";

strReturn = Substring(strData, 0, 0 );               // ""
strReturn = Substring(strData, 0, 12);             // "0123456789"
strRetrun = Substring(strData, 13, 10);          // ""
strReturn = Substring(strData, 9, 3);             // "9"
strReturn = Substring(strData, 0, 3);             //"012"