CODEWITHSUNDEEP
c#regex
Daniel Lip
Daniel Lip

Reputation: 11335

Im trying to parse all links from a website but it doesn't work what could be wrong?

Im using this code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
using System.Text.RegularExpressions;
using HtmlAgilityPack;

namespace HtmlParser
{
    public partial class Form1 : Form
    {

        // The HtmlWeb class is a utility class to get the HTML over HTTP
        HtmlWeb htmlWeb = new HtmlWeb();

        // Creates an HtmlDocument object from an URL
        HtmlAgilityPack.HtmlDocument document;

        // Targets a specific node
        HtmlNode someNode;

        public Form1()
        {
            InitializeComponent();
            document = htmlWeb.Load("http://www.walla.co.il");
            someNode = document.GetElementbyId("mynode");

            // If there is no node with that Id, someNode will be null
            if (someNode != null)
            {
                // Extracts all links within that node
                IEnumerable<HtmlNode> allLinks = someNode.Descendants("a");

                // Outputs the href for external links
                foreach (HtmlNode link in allLinks)
                {
                    // Checks whether the link contains an HREF attribute
                    if (link.Attributes.Contains("href"))
                    {
                        // Simple check: if the href begins with "http://", prints it out
                        if (link.Attributes["href"].Value.StartsWith("http://"))
                            richTextBox1.Text = link.Attributes["href"].Value.ToString();
                    }
                }
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }


    }
}

But it never pass the line :

someNode = document.GetElementbyId("mynode");

Used a breakpoint on this line and its giving me a message: No Source Is Available If im not using a break point nothing happen the program is running but im not getting any errors but it also doesn't work.

What should i do ? I didn't understand what should i put there instead of "my node"

Upvotes: 0

Views: 144

Answers (1)

Mark Byers
Mark Byers

Reputation: 838916

The probem is trying to use regex to parse HTML.

The specific cause of the error is that you have a ? and a newline character that shouldn't be there, and this causes the regular expression to be invalid.

You can fix it by using HtmlAgilityPack instead.

Upvotes: 2

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