Extracting a picture address in C # HTML

public class HtmlHelper
???? {
???????? <summary>
???????? Extracting image addresses in HTML
???????? </summary>
???????? public static list<string> Pickupimgurl (string html)
???????? {
???????????? Regex regimg = new Regex (@ "]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[" "']?[ \s\t\r\n]* (? [^\s\t\r\n "" ' <>]* ") [^<>]*?/? [\s\t\r\n]*> ", regexoptions.ignorecase);
???????????? MatchCollection matches = regimg.matches (HTML);
???????????? list<string> lstimg = new list<string> ();

???????????? foreach (match match in matches)
???????????? {
???????????????? Lstimg.add (match. groups["Imgurl"]. Value);
????????????}

???????????? return lstimg;
????????}

???????? <summary>
???????? Extracting image addresses in HTML
???????? </summary>
???????? public static string Pickupimgurlfirst (string html)
???????? {
???????????? list<string> lstimg = pickupimgurl (HTML);

???????????? return Lstimg.count = = 0? String. EMPTY:LSTIMG[0];
????????}
????}

Extracting a picture address in C # HTML