How do I extract number from string and parse it as date?

\d{8}

DateTime dt;
if (!DateTime.TryParseExact(yourStringBasedDate, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None, out dt))
    {
    // report problem or log it
    return;
    }

System.Globalization.CultureInfo ci = System.Globalization.CultureInfo.InvariantCulture;
string[] files = {"uk_mcn_20190201_feed.xml",
	"uk_20190202_mcn_feed.xml",
	"20190203_uk_mcn_feed.xml",
	"uk_mcn_feed_20190204.xml"};
	
var filesAndDates =  files
	.Select(x=> new 
		{
			FileName = x,
			Date = DateTime.ParseExact(Regex.Replace(x, @"\D", ""), "yyyyMMdd", ci) //here non-digits are replaced with empty string
		})
	.ToList();
	
foreach(var fad in filesAndDates)
{
	Console.WriteLine("{0}\t{1}", fad.FileName, fad.Date);
}