How to use FindResourceW() Properly?

Question

A simple example here I want to load some embedded text file to my application but when I use FindResourceW I get compile-time error:

HGLOBAL     res_handle = NULL;
HRSRC       res;
wchar_t*    res_data;
DWORD       res_size;

// NOTE: providing g_hInstance is important, NULL might not work
res = FindResourceW(GetModuleHandleW(NULL), MAKEINTRESOURCEW(MY_RESOURCE), RT_RCDATA);
if (!res)
    return 1;

In my .rc file I defined the resource like this:

MY_RESOURCE RCDATA    L"Help topics.txt"

The error:

Severity Code Description Project File Line Error C2664 'HRSRC FindResourceW(HMODULE,LPCWSTR,LPCWSTR)': cannot convert argument 3 from 'LPSTR' to 'LPCWSTR' FindFilesProj C:\Users\WongFei\Desktop\FindFilesProj UNICODE\WinMain.cpp 674

But I think it is defined by default in `msvc++ 14.0` isn't it? — WonFeiHong, Nov 08 '17 at 12:53
defined `RT_RCDATA` as `MAKEINTRESOURCE(10)` . `MAKEINTRESOURCE` defined as `MAKEINTRESOURCEW` if defined `UNICODE` otherwise as `MAKEINTRESOURCEA` - from your error visible that `RT_RCDATA` expanded to `MAKEINTRESOURCEA` - so you need define `UNICODE` in project settings — RbMm, Nov 08 '17 at 12:55
@RbMm: `MY_RESURCE` is defined in the header file and in `rc` file. — WonFeiHong, Nov 08 '17 at 12:59
if *but nothing loaded* faster of all resource not found in exe. usual due different resource name. look in pe viewer how actual your resource named — RbMm, Nov 08 '17 at 13:02
Now the return value is null `if(!res)` succeeds! What is the problem now? — WonFeiHong, Nov 08 '17 at 13:02
are `#define MY_RESOURCE 1000` visible in rc file ? you include `myres.h` to it ? — RbMm, Nov 08 '17 at 13:11
of course in this case `.rc` can not know that `MY_RESOURCE` is 1000 (from where ? why not 453 ?) and treat it as string `"MY_RESOURCE"` — RbMm, Nov 08 '17 at 13:14
@RbMm: If you posted it as an answer it'll be an accepted good answer. — WonFeiHong, Nov 08 '17 at 13:15
@xMRi: I saved it with `notepad++` as `UTF-8 BOM` but it doesn't help? — WonFeiHong, Nov 08 '17 at 13:38
Windows uses UTF-16. In you case you have to convert it after loading using MultiByteToWideChar. — xMRi, Nov 08 '17 at 13:39
REad the MSDN Doku. There are thousand samples in the net. Just Google: This was the first link I found in [SO](https://stackoverflow.com/questions/10766838/converting-file-in-utf-8-to-utf-16) — xMRi, Nov 08 '17 at 13:43
Please stop changing the question. Your next problems are not part of this question. — David Heffernan, Nov 08 '17 at 14:17
But there's also no point asking a new question about that because it has been asked hundreds of times already. — David Heffernan, Nov 08 '17 at 14:23

score 3 · Accepted Answer · edited Nov 08 '17 at 20:40

3

You are using RT_RCDATA, which is defined as:

#define RT_RCDATA           MAKEINTRESOURCE(10)

And MAKEINTRESOURCE() is defined as:

#define MAKEINTRESOURCEA(i) ((LPSTR)((ULONG_PTR)((WORD)(i))))
#define MAKEINTRESOURCEW(i) ((LPWSTR)((ULONG_PTR)((WORD)(i))))
#ifdef UNICODE
#define MAKEINTRESOURCE  MAKEINTRESOURCEW
#else
#define MAKEINTRESOURCE  MAKEINTRESOURCEA
#endif // !UNICODE

You have a project were UNICODE isn't defined. So MAKEINTRESOURCE() returns a char* but FindeResourceW() wants a wchar_t* instead. Thus the compiler error. You can't use RT_RCDATA as-is in combination with FindResourceW() when UNICODE isn't defined.

Use FindResource() instead of FindResourceW(). This makes sure that MAKEINTRESOURCE() returns a pointer of the same type (UNICODE or non-UNICODE) that FindResource() expects:

res = FindResource(GetModuleHandle(NULL), MAKEINTRESOURCE(MY_RESOURCE), RT_RCDATA);

Otherwise, you have to type-cast RT_RCDATA to wchar_t* to match what FindResourceW() expects:

 res = FindResourceW(GetModuleHandleW(NULL), MAKEINTRESOURCEW(MY_RESOURCE), (LPWSTR)RT_RCDATA);

The type-cast is safe.

Remember that your resource is stored in the way you created it. There may be need to convert it into the proper character mode you need.

edited Nov 08 '17 at 20:40

Remy Lebeau

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answered Nov 08 '17 at 12:56

xMRi

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2

The problem is with `RT_RCDATA` because `UNICODE` is not defined. – David Heffernan Nov 08 '17 at 13:08
Jupp RT_RCDATA sis defined as MAKEINTRESOURCE(10). So the conflict is there. And there is no RT_RCDATAA and RT_RCDATAW – xMRi Nov 08 '17 at 13:30
Changed my answer. – xMRi Nov 08 '17 at 13:36
No need for the resource itself to be Unicode encoded – David Heffernan Nov 08 '17 at 14:02
Yes. I Just read his changed question again... and answered accordingly. You are right.... I change the text again. – xMRi Nov 08 '17 at 14:05
@xMRi: I am so sorry for changing the topic. – WonFeiHong Nov 08 '17 at 19:32

How to use FindResourceW() Properly?

1 Answers1