Prints last error by GetLastError(), FormatMessageA().

PrintLastError();

#include <stdlib.h>
#include "windows.h"

void PrintLastError()
{
	//Get the error message, if any.
	DWORD errorMessageID = ::GetLastError();
	if (errorMessageID == 0)
	{
		return; //No error message has been recorded
		printf("No error.\n");
	}
		
	LPSTR messageBuffer = nullptr;
	size_t size = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
								 NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)& messageBuffer, 0, NULL);

	printf("%s\n", messageBuffer);
	//Free the buffer.
	LocalFree(messageBuffer);
}