Regular Expression to find src from IMG tag

Question

I have a web page. From that i want to find all the IMG tags and get the SRC of those IMG tags.

What will be the regular expression to do this.

Some explanation:

I am scraping a web page. All the data is displayed correctly except the images. To solve this, wow i have an idea, to find the SRC and replace it : e.g

/images/header.jpg

and replace this with

www.stackoverflow/images/header.jpg

Solution 1

You don't want a regular expression, you want a parser. From this question:

class Program
{
    static void Main(string[] args)
    {
        var web = new HtmlWeb();
        var doc = web.Load("http://www.stackoverflow.com");

        var nodes = doc.DocumentNode.SelectNodes("//img[@src]");

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

Solution 2

As pointed out, regular expression are not the perfect solution, but you can usually build one that is good enough for the job. This is what I would use:

string newHtml = Regex.Replace(html,
      @"(?<=<img\s+[^>]*?src=(?<q>['""]))(?<url>.+?)(?=\k<q>)",
      m => "http://www.stackoverflow.com" + m.Value);

It will match src attributes delimited by single or double quotes.

Of course, you would have to change the lambda/delegate to do your own replacing logic, but you get the idea :)