formatmessage

I have been using the FormatMessage function within the Windows API to generate message strings from system error codes. I noticed that for some error codes the full message doesn't appear to be created. Take this sample program as an example: int main() { wchar_t * buffer = nullptr; FormatMessageW( FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr, ERROR_SYSTEM_PROCESS_TERMINATED, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), reinterpret_cast<LPWSTR>(&buffer), 0, nullptr); std::wcout << buffer << std::endl; return 0; } According to MSDN I should

I'm running this to test FormatMessage : LPVOID lpMsgBuf; errCode=12163; FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM , 0, errCode, 0, (LPTSTR) &lpMsgBuf, 0, NULL ); However, when it returns lpMsgBuf contains NULL... I was expecting something like ERROR_INTERNET_DISCONNECTED . Anything look wrong? Thanks. Shog9 That's a WinINet error, and so the message associated with it lives in WinINet.dll. You just need to tell FormatMessage() about this in order for it to retrieve the correct message: FormatMessage( // flags: FORMAT_MESSAGE_ALLOCATE_BUFFER // allocate buffer

Without : MFC ATL How can I use FormatMessage() to get the error text for a HRESULT ? HRESULT hresult = application.CreateInstance("Excel.Application"); if (FAILED(hresult)) { // what should i put here to obtain a human-readable // description of the error? exit (hresult); } Shog9 Here's the proper way to get an error message back from the system for an HRESULT (named hresult in this case, or you can replace it with GetLastError() ): LPTSTR errorText = NULL; FormatMessage( // use system message tables to retrieve error text FORMAT_MESSAGE_FROM_SYSTEM // allocate buffer on local heap for error