Code : Get any attribute value from HTML string in C#

If you have HTML string in C# and you want to get any particular value of any attribute then you can use below function which refer Regex to get its value.

In below program I am extraing “src” attribute value of HTML “img" tag.

Input string : <img alt="" src="/MediaCenter/PublishImages/DSC_0134.jpg" width="150" style="border:0px solid" />

Output : /MediaCenter/PublishImages/DSC_0134.jpg

Code:

using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

namespace Rextester

{

    public class Program

    {

        public static void Main(string[] args)

        {

            string s = "<img alt=\"\" src=\"/MediaCenter/PublishImages/DSC_0134.jpg\" width=\"150\" style=\"border:0px solid\" />";

            var srcs = GetSrcInHTMLImgString(s);

            Console.WriteLine(srcs[0]);//Output: /MediaCenter/PublishImages/DSC_0134.jpg

        }

        public static List<string> GetSrcInHTMLImgString(string htmlString)

        {

            List<string> srcs = new List<string>();

            string pattern = @"(?<=src="").*?(?="")";

           

            Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);

            MatchCollection matches = rgx.Matches(htmlString);

            for (int i = 0, l = matches.Count; i < l; i++)

            {

                string d = matches[i].Value;

                srcs.Add(d);

            }

            return srcs;

        }

    }

}

We can make this function more generic where we will pass any attribute name and get the value as

public static List<string> GetAttributeNameInHTMLString(string htmlString, string attributeName)

{

    List<string> attributeValues = new List<string>();

    string pattern = string.Format(@"(?<={0}="").*?(?="")", attributeName);

    Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);

    MatchCollection matches = rgx.Matches(htmlString);

    for (int i = 0, l = matches.Count; i < l; i++)

    {

        string d = matches[i].Value;

        attributeValues.Add(d);

    }

    return attributeValues;

}

Calling this function as

string s = "<img alt=\"\" src=\"/MediaCenter/PublishingImages/DSC_0134.jpg\" width=\"150\" style=\"border:0px solid\" />";

var widths = GetAttributeNameInHTMLString(s, "width");

Console.WriteLine(widths[0]);   //Output : 150

var styles = GetAttributeNameInHTMLString(s, "style");

Console.WriteLine(styles[0]);   //Output : border:0px solid

Its a small function but very handy. 

To test it, you can use C# online compiler “.NET Fiddle” instead of creating console application in Visual Studio. Many times I am using these online tools for quick testing. 

Let me know if you have any better idea to get attribute value from HTML string.