.net 文字调用文字限制

public static string StringTruncat(string oldStr, int maxLength, string endWith)
{
if (string.IsNullOrEmpty(oldStr))
//   throw   new   NullReferenceException( "原字符串不能为空 ");
return oldStr + endWith;
if (maxLength < 1)
throw new Exception("返回的字符串长度必须大于[0] ");
if (oldStr.Length > maxLength)
{
string strTmp = oldStr.Substring(0, maxLength);
if (string.IsNullOrEmpty(endWith))
return strTmp;
else
return strTmp + endWith;
}
return oldStr;
}

<%# StringTruncat(Eval("PinPaiPingJia").ToString(), 100, "...")%>