Enumerate serial ports

One of the posts that keeps reappearing in the programming newsgroups is how to enumerate all the serial ports installed. The problem is that there is no standard Win32 API call which allows serial port enumeration. The approach that this code uses is calling CreateFile directly. If the port cannot be opened, the code examines the error code to see if it was accessed denied error in which case it knows that the port exists even though it could not open the port. .