使用 c# 脚本从 HTML 文件中提取数据

Question

What I need to do : Extract (Information of From, To, Cc and Subject ) and remove them from HTML file. Without the use of any 3rd party ( HTMLAgilityPack, etc)

What I am having trouble with : What will be my approach to get the following(from,to,subject,cc) from the html tags?

Steps I tried: I tried to get the index of <p class=MsoNormal> and the last index of the email @sampleemail.com but I think that is a bad approach since in some html files there will be a lot of " <p class=MsNormal> ", regarding the removal of the from,to,cc and subject I just used the string.Remove(indexOf, i counted the characters from indexOf to lastIndexOf ) function and it worked

Sample tag containing information of from:

<p class=MsoNormal style='margin-left:120.0pt;text-indent:-120.0pt;tab-stops:120.0pt;mso-layout-grid align:none;text-autospace:none'><b><span style='color:black'>From:<span style='mso-tab-count:1'></span></span></b><span style='color:black'>1234@sampleemail.com<o:p></o:p></span></p>                                     

HTML FILE output:

Answer 1

HTMLAgilityPack is your friend. Simply using XPath like //p[@class ='MsoNormal'] to get tags content in HTML

public static void Main()
{
    var html =
    @"<p class=MsoNormal style='margin-left:120.0pt;text-indent:-120.0pt;tab-stops:120.0pt;mso-layout-grid align:none;text-autospace:none'><b><span style='color:black'>From:<span style='mso-tab-count:1'></span></span></b><span style='color:black'>1234@sampleemail.com<o:p></o:p></span></p>                                     ";

    var htmlDoc = new HtmlDocument();
    htmlDoc.LoadHtml(html);

    var nodes = htmlDoc.DocumentNode.SelectNodes("//p[@class ='MsoNormal']");

    foreach(var node in nodes)
        Console.WriteLine(node.InnerText);      
}

Result:

From:1234@sampleemail.com

---

Update

We may use Regex to write this simple parser. But remember that it cannot clear all cases for complicated html document .

    public static void MainFunc()
    {
        string str = @"<p class='MsoNormal' style='margin-left:120.0pt;text-indent:-120.0pt;tab-stops:120.0pt;mso-layout-grid align:none;text-autospace:none'><b><span style='color:black'>From:<span style='mso-tab-count:1'></span></span></b><span style='color:black'>1234@sampleemail.com<o:p></o:p></span></p>                                     ";
        var result = Regex.Replace(str, "<(?:\"[^\"]*\"['\"]*|'[^']*'['\"]*|[^'\">])+>", "");
        Console.WriteLine(result);
    }