ASP.NET 獲得指定字符串中開始和結束中間的值

/// <summary>       

/// 獲得字符串中開始和結束字符串中間得值
/// </summary>    
/// <param name="str"></param>      
/// <param name="beginStr">開始</param>    
/// <param name="endStr">結束</param>       
/// <returns></returns>       
private static string GetStr(string str, string beginStr, string endStr)
{
   Regex rg = new Regex("(?<=(" + beginStr + "))[.\\s\\S]*?(?=(" + endStr + "))", RegexOptions.Multiline | RegexOptions.Singleline);
    return rg.Match(str).Value;

}

使用方法：

string oldStr = @"<b>我的博客地址</b>http://www.568387.com/blog/";
string newStr =GetStr(oldStr, "<b>", "</b>");
//結果：我的博客地址

  string newoldstr = oldStr.Replace(GetStr(oldStr, "<b>", "</b>"), "PigBlogs");
//結果：<b>PigBlogs</b>http://www.568387.com/blog/