c# regular expression for finding links in with specific ending

Question

I need a regex pattern for finding links in a string (with HTML code) to get the links with file endings like .gif or .png

Example String:

Answer 1

I can suggest using HtmlAgilityPack for this task. Install using Manage NuGet Packages for Solution menu, and add the following method:

/// <summary>
/// Collects a href attribute values and a node values if image extension is jpg or png
/// </summary>
/// <param name="html">HTML string or an URL</param>
/// <returns>A key-value pair list of href values and a node values</returns>
private List<KeyValuePair<string, string>> GetLinksWithHtmlAgilityPack(string html)
{
    var result = new List<KeyValuePair<string, string>>();
    HtmlAgilityPack.HtmlDocument hap;
    Uri uriResult;
    if (Uri.TryCreate(html, UriKind.Absolute, out uriResult) && uriResult.Scheme == Uri.UriSchemeHttp)
    { // html is a URL 
        var doc = new HtmlAgilityPack.HtmlWeb();
        hap = doc.Load(uriResult.AbsoluteUri);
    }
    else
    { // html is a string
        hap = new HtmlAgilityPack.HtmlDocument();
        hap.LoadHtml(html);
    }
    var nodes = hap.DocumentNode.SelectNodes("//a");
    if (nodes != null)
        foreach (var node in nodes)
            if (Path.GetExtension(node.InnerText.Trim()).ToLower() == ".png" ||
                    Path.GetExtension(node.InnerText.Trim()).ToLower() == ".jpg")
            result.Add(new KeyValuePair<string,string>(node.GetAttributeValue("href", null), node.InnerText));
    return result;
}

Then, use it as (I am using a dummy string, just for demo)

var result = GetLinksWithHtmlAgilityPack("<a href=\"//site.com/folder/picture.png\" target=\"_blank\">picture.png</a><a href=\"//site.com/folder/picture.bmp\" target=\"_blank\">picture.bmp</a>");

Output:

Or, with a URL, something like:

var result = GetLinksWithHtmlAgilityPack("http://www.google.com");