Regular expression for HTML anchor Tag

hi,
I was in search of finding a regular expression that matches the anchor tag in HTML and updates the value of the href attributes.

i have gone through many of them but none supports the anchor tag in which the qoutes around href are not present i.e.
<a href=www.gmail.com>google</a>
so here in the updated Regular expression that matches all kinds of anchor tag and then a small chunk of c# code to get and update the value of href attribute.

@"<a.*?href=([""'])?(?<url>.*?)[""?|'?].*?>(?<name>.*?)</a>";
public string UpdateHTMLAnchorTag(string input)
{
string initialURL = PLACE THE ABOVE REGULAR EXPRESSION HERE
Regex regex = new Regex(initialURL, RegexOptions.IgnorePatternWhitespace | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(input);
string ma = string.Empty;
foreach (Match m in matches)
{
ma = m.Result("${url}");
input = input.Replace(tempMa, "UpdatedMA");


}
return input;

}