A simple sample for async write to file in C++

Async write to file C++ - sample

#include "pch.h"
#include <iostream>
#include <Windows.h>
#include <atlstr.h>


VOID WINAPI FileWrittenCallback(DWORD dwErrorCode, DWORD dwBytesTransferred, LPOVERLAPPED lpOverlapped) {
	if (dwErrorCode != 0) {
		fprintf(stdout, "CompletionRoutine: Unable to write to file! Error: %u, AddrOverlapped: %p\n", dwErrorCode, lpOverlapped);
	}
	else {
		fprintf(stdout, "CompletionRoutine: Transferred: %u Bytes, AddrOverlapped: %p\n", dwBytesTransferred, lpOverlapped);
	}
}

int main()
{
	HANDLE hFile = CreateFile(_T("K:\\foo.txt"), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
	if (INVALID_HANDLE_VALUE == hFile) {
		fprintf(stdout, "Could not create file! Error %u\n", GetLastError());
		return -1;
	}

	OVERLAPPED oFile;
	oFile.Offset = 0xFFFFFFFF;
	oFile.OffsetHigh = 0xFFFFFFFF;

	CString text = _T("Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy\r\n");
	if (!WriteFileEx(hFile, text, text.GetLength() * 2, &oFile, (LPOVERLAPPED_COMPLETION_ROUTINE)FileWrittenCallback)) {
		fprintf(stdout, "Unable to write to file! Error %u\n", GetLastError());
	}
	CloseHandle(hFile);
	return 0;
}