或者，您可以通过这种方式完成

Alternatively, you can do it by this way

string str = "112192";
DateTime date = DateTime.ParseExact(str, "MMddyy", CultureInfo.InvariantCulture);
Console.WriteLine(date.ToString("yyyy"));

此外，您的方法正在起作用

Also, your approach is working

DateTime date;
string str = "112192";
bool success = DateTime.TryParseExact(str, "MMddyy", System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out date);
Console.WriteLine(date.ToString("yyyy"));