字符串处理

 public sealed class CleanString
 {
  /// <summary>
  /// 输入替换
  /// </summary>
  /// <param name="inputString"></param>
  /// <param name="maxLength"></param>
  /// <returns></returns>
  public static string InputText(string inputString, int maxLength)
  {   
   StringBuilder retVal = new StringBuilder();

   if ((inputString != null) && (inputString != String.Empty))
   {
    inputString = inputString.Trim();

    if (inputString.Length > maxLength)
    {
     inputString = inputString.Substring(0, maxLength);
    }

    for (int i = 0; i < inputString.Length; i++)
    {
     switch(inputString[i])
     {
      case '"':
       retVal.Append("&quot;");
       break;
      case '<':
       retVal.Append("&lt;");
       break;
      case '>':
       retVal.Append("&gt;");
       break;
      case ' ':
       retVal.Append("&nbsp;");
       break;
      case (char)13:
       retVal.Append("<br />");
       break;
      default:
       retVal.Append(inputString[i]);
       break;
     }
    }

    retVal.Replace("'", "");
   }

   return retVal.ToString();   
  }

  /// <summary>
  /// 输出替换
  /// </summary>
  /// <param name="inputString"></param>
  /// <returns></returns>
  public static string OutputText(string inputString)
  {   
   StringBuilder retVal = new StringBuilder(inputString.Trim());

   if ((inputString != null) && (inputString != String.Empty))
   {
    retVal.Replace("&quot;","\"");
    retVal.Replace("&lt;","<");
    retVal.Replace("&gt;",">");
    retVal.Replace("&amp;","&");
    retVal.Replace("&nbsp;"," ");
   }

   return retVal.ToString();   
  }

  /// <summary>
  /// 截取固定长度字符串
  /// </summary>
  /// <param name="inputString"></param>
  /// <param name="len"></param>
  /// <returns></returns>
  public static string CutString(string inputString,int len)
　　{
   int tempLen = 0;
   string tempString = "";

   ASCIIEncoding ascii = new ASCIIEncoding();
   byte[] s = ascii.GetBytes(inputString);
   
   for(int i = 0;i < s.Length;i++)
   {
    if((int)s[i] == 63)
    {
     tempLen += 2;
    }
    else
    {
     tempLen += 1;
    }

    try
    {
     tempString += inputString.Substring(i,1);
    }
    catch
    {
     break;
    }

    if(tempLen>len)
    {
     break;
    }
   }

   //如果截过则加上半个省略号
   byte[] mybyte = System.Text.Encoding.Default.GetBytes(inputString);
   if(mybyte.Length>len)
   {
    tempString += "…";
   }

   return tempString;
  }
  
  //kill掉标签
  public static string StripHT(string strHtml)
  {
   Regex regex=new Regex("<.+?>",RegexOptions.IgnoreCase);
   string strOutput=regex.Replace(strHtml,"");
   return strOutput;
  }

 }