有用的String的扩展

1. 将字符串数组用一个符号连接起来
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   public static class StringExtendsions {     /// <summary>     /// 将字符串数组用一个符号连接起来     /// </summary>     /// <param name="items">数组</param>     /// <param name="joinFlag">符合，比如中文的逗号“，”</param>     /// <returns></returns>     public static string ToJoinString(this string[] items, string joinFlag)     {         if (items == null || items.Length == 0)         {             return string.Empty;         }         System.Text.StringBuilder result = new System.Text.StringBuilder();         int i = 1;         int itemLength = items.Length;         foreach (string item in items)         {             result.Append(item);             if (!string.IsNullOrEmpty(joinFlag) && i < itemLength)             {                 result.Append(joinFlag);             }             i++;         }         return result.ToString();     } }

2. 移除HTML代码
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   public static class StringExtensions {     /// <summary>     /// 移除HTML代码     /// </summary>     /// <param name="Htmlstring">要移除的字符串</param>     /// <returns></returns>     public static string RemoveHTML(this string Htmlstring)     {         //删除脚本         Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"<script[^>]*?>.*?</script>", "", RegexOptions.IgnoreCase);         //删除HTML         Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"<!--.*", "", RegexOptions.IgnoreCase);         //Htmlstring = Regex.Replace(Htmlstring,@"<A>.*</A>","");         //Htmlstring = Regex.Replace(Htmlstring,@"<[a-zA-Z]*=\.[a-zA-Z]*\?[a-zA-Z]+=\d&\w=%[a-zA-Z]*|[A-Z0-9]","");         Htmlstring = Regex.Replace(Htmlstring, @"&(quot|#34);", "\"", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(amp|#38);", "&", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(lt|#60);", "<", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(gt|#62);", ">", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(nbsp|#160);", " ", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(iexcl|#161);", "\xa1", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(cent|#162);", "\xa2", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(pound|#163);", "\xa3", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&(copy|#169);", "\xa9", RegexOptions.IgnoreCase);         Htmlstring = Regex.Replace(Htmlstring, @"&#(\d+);", "", RegexOptions.IgnoreCase);         Htmlstring.Replace("<", "");         Htmlstring.Replace(">", "");         Htmlstring.Replace("\r\n", "");         //Htmlstring=HttpContext.Current.Server.HtmlEncode(Htmlstring).Trim();         return Htmlstring;     } }

3. 截取并省略字符串
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   /// <summary> /// 截取并省略字符串 /// </summary> /// <param name="str"></param> /// <param name="length">需要截取的字符长度</param> /// <returns></returns> public static string SubstringEllipsis(this string str, int length) {     if (str == null)     {         return null;     }     string result = GetSubString(str.ToString(), length);     if (str.ToString().Length > result.Length)     {         result += "...";     }     return result; }   /// <summary> /// 获取指定字符串从 0 开始指定长度的字符。单个字符若是双字节长度算 1 若为单字节长度算 0.5。 /// </summary> /// <param name="input">需要获取的字符串</param> /// <param name="count">需要获取的长度</param> /// <returns></returns> private static string GetSubString(string input, int count) {     int outputCount = 0;     bool appendCount = false; // 是否递增长度     string output = "";       foreach (Char c in input.ToCharArray())     {         if (outputCount >= count)         {             break;         }         if (Regex.IsMatch(c.ToString(), @"[^\x00-\xff]"))         {             outputCount++; // 双字节算长度 1         }         else         {             // 单字节算长度 0.5             if (!appendCount)             {                 appendCount = true;             }             else             {                 appendCount = false;                 outputCount++;             }         }         output += c.ToString();     }     return output; }