Get html tag using regex .net

Let say you want to get a specific tag from the html, you need to use regex to scan and grab it. here is the example :)

private string FixedImgHtml(string html, int fixedwidth)
{
string input = html;
MatchCollection mc = Regex.Matches(input, "<img[a-zA-Z0-9_\\^\\$\\.\\\\{\\[\\}\\]\\(\\)\\*\\+\\?\\\\~`!@#%&-=;:'\",/\\n\\s]*>", RegexOptions.IgnoreCase);
foreach (Match m in mc)
{
input = input.Replace(m.Value, m.Value + " onload='AutoImageResizing(this, "+ fixedwidth.ToString()+")'");
}
return input;
}