Why does WriteFile not run more than once? - c++

Question

Here's my code in which I've got on an infinite loop (to my knowledge)
while(true) {
DWORD TitleID = XamGetCurrentTitleId();
std::ostringstream titleMessageSS;
titleMessageSS << "Here's the current title we're on : " << TitleID << "\n\n";
std::string titleMessage = titleMessageSS.str(); // get the string from the stream
DWORD dwBytesToWrite = (DWORD)titleMessage.size();
DWORD dwBytesWritten = 0;
BOOL bErrorFlag = FALSE;
HANDLE logFile = CreateFile( "Hdd:\\LOGFile.txt", GENERIC_WRITE, 0, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, NULL);
bErrorFlag = WriteFile(logFile, titleMessage.c_str(), dwBytesToWrite, &dwBytesWritten, NULL);
CloseHandle(logFile);
Sleep(30000);
}
return NULL;
Does anyone see a reason as to why this only writes just once? I've waited over 5 minutes to see if it does anything in the end to no avail.

Answer 1

The Flag CREATE_NEW in CreateFile prevents the update of the file because CreateFile fail with ERROR_FILE_EXISTS. Use OPEN_ALWAYS instead.
Also it will always truncate. Replace GENERIC_WRITE with FILE_APPEND_DATA if you want to add a new line at the end of your logfile.
The whole CreateFile line should be:
HANDLE logFile = CreateFile( "Hdd:\\LOGFile.txt", FILE_APPEND_DATA , 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
Read CreateFile documentation carefully, it worth it, because it has a central role in the windows IO universe:
https://msdn.microsoft.com/en-us/library/windows/desktop/aa363858(v=vs.85).aspx
look also add:
https://stackoverflow.com/a/9891875/1922748

Answer 2

As Martin James mentioned, from MSDN:
CREATE_NEW
Creates a new file, only if it does not already exist.
If the specified file exists, the function fails and the last-error
code is set to ERROR_FILE_EXISTS (80).
If the specified file does not exist and is a valid path to a writable
location, a new file is created.
So it seems that the handle is invalid after the first call, and hence WriteFile() fails.