Last write FILETIME always returning current time - c++

Question

I need to compare a file's last modified time to a date time stored in a database. I initially looked at this question to get started.
I am currently getting the FILETIME for the last write of the file, converting it to a SYSTEMTIME. Then I use that SYSTEMTIME to create a TDateTime object that I can use for my comparison. However, the FileModifiedDT variable, is always coming out to be the current time, despite the file having been modified previously.
FILETIME lastWriteTime;
String * FileNamePtr = new String( FileName );
GetFileTime( FileNamePtr, NULL, NULL, &lastWriteTime );
SYSTEMTIME systemTime;
FileTimeToSystemTime( &lastWriteTime, &systemTime );
TDateTime * FileModifiedDT = new TDateTime( systemTime.wYear, systemTime.wMonth,
systemTime.wDay, systemTime.wHour,
systemTime.wMinute, systemTime.wSecond,
systemTime.wMilliseconds );
Am I missusing GetFileTime in some way? Is there a better way I should go about this?

Answer 1

The error is
String * FileNamePtr = new String( FileName );
GetFileTime( FileNamePtr, NULL, NULL, &lastWriteTime );
According to the documentation, the first argument has to be a file handle created by CreateFile and nothing else.
Thus you need something like this:
HANDLE fileHandle = CreateFile(
FileName, //LPCTSTR
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL
);
if ( fileHandle != INVALID_HANDLE )
{
GetFileTime( fileHandle, NULL, NULL, &lastWriteTime );
CloseHandle( fileHandle );
}
else
{
// error, do something else...
}