Get ID value from html string

Question

I grabbed outlook's appointment description and got this string:

<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
  ID: 123456<br>
  Comments: blah blah
</body>
</html>

I need to get ID value 123456 and Comments value out with c# code. I can only use standard .NET library, that is, I can't use html agility pack. I did something like this:

var index = html.IndexOf("ID");
var IDindex = index + "ID".Length + 2 ;
var IDvalue = html.Substring( IDIndex,6);

But I like to do something more robust to handle for example ID length change.

You could definitely write a regular expression to extract it. — ameer, Dec 07 '17 at 19:45
A more robust solution is to use Html Agility Pack or some other library that is specifically designed to parse HTML. — crashmstr, Dec 07 '17 at 19:47
@ameer Obvious troll re: https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 ? — Yuck, Dec 07 '17 at 19:47
@crashmstr OP states _I can only use standard .NET library, that is, I can't use html agility pack_ — Yuck, Dec 07 '17 at 19:48
@Yuck yes, but that is the *robust answer*. Nothing else will be *robust*. Sometimes it is better to change the rules than write fragile code. — crashmstr, Dec 07 '17 at 19:49
@Yuck see also: [Kobayashi Maru](https://en.wikipedia.org/wiki/Kobayashi_Maru) — crashmstr, Dec 07 '17 at 19:57
You're not trying to parse/interpret HTML, you're just trying to extract a value from a string. Regex is just fine `ID: ([0-9]{1,})\
` — Paul Abbott, Dec 07 '17 at 20:02
Parsing HTML with regex is not recommended, you can get varied results. — EasyE, Dec 07 '17 at 20:20

ameer · Accepted Answer · 2017-12-07T21:08:36.857

I would try something with a regular expression match and checking the 1st captured group of a regex like ID:\s*(\d+)<br />

using System;
using System.Text.RegularExpressions;

namespace RegexExample
{
    class Program
    {
        static void Main(string[] args)
        {
            foreach (Match match in Regex.Matches("ID: 12345<br />", @"ID:\s*(\d+)<br />"))
                Console.WriteLine(match.Groups[1]);
        }
    }
}

Get ID value from html string

1 Answers1