CODEWITHSUNDEEP
c++visual-c++visual-studio-2013
user34537
user34537

Reputation:

Resource in MSVC++ 2013

I want to access my resource as a char* or vector or a FILE. I tried the below and I got null. I don't understand why. The first parameter is optional the last I took from the documentation page. RT_RCDATA seems to be what I want. IDK why I am getting null

HRSRC rc = FindResourceEx(0, RT_RCDATA, MAKEINTRESOURCE(IDR_MyResource), MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL));

I get the error 1813. I have a single executable with no dlls. The resource is in the executable

Upvotes: 3

Views: 265

Answers (2)

WhozCraig
WhozCraig

Reputation: 66254

Answering (I hope) this question and your prior question here, This answer applies to FindResource, though you can adapt to FindResourceEx

The parameters to FindResource are module-to-search, id, and type.

  • The first is the instance handle who'd resource table to search. You can use NULL for the running process, Otherwise this is in a DLL you need to save off your instance handle from DllMain, usually in a global ghInst, and use that for your search target.

  • The second should be your resource id. If you're using macro ids such as from a resource.h header, the id must be wrapped with MAKEINTRESOURCE(id). Otherwise its the same string (as a string) you used for your resource id.

  • The third is the resource type. When you declared your custom resource you gave it a type in your resource script (something like MYRES; Ex: I use XML for xml files, for example). The type parameter is that value as a string.

Therefore, finding the custom resource of id MY_ID (taken from an included resource.h id file) of type MYDATA in the current processes resource table would be:

HRSRC hRes = FindResource(NULL, MAKEINTRESOURCE(MY_ID), _T("MYDATA"));

Similarly, loading the same resource from a DLL resource table, assuming you saved the instance handle of the DLL to some global ghInst in the PROCESS_ATTACH of your DllMain, is:

HRSRC hRes = FindResource(ghInst, MAKEINTRESOURCE(MY_ID), _T("MYDATA"));

Missing ID

It is not uncommon to "forget" to properly declare the identifier used for the resource in a .h file that is included in the resource script and C/C++ code, but the resource script will happily still compile. If the following is in your resource script

MY_ID MYDATA "filename.bin"

and MY_ID is not defined via macro as a numeric id and included in your resource script, this will "name" a resource called "MY_ID" (note its a string) in the output resource table. Worse, if the id-defining-macro is properly included in the C/C++ code trying to load this thing, then this:

HRSRC hRes = FindResource(NULL, MAKEINTRESOURCE(MY_ID), _T("MYDATA"));

will compile, since the C/C++ code has MY_ID properly available, but the resulting id is not the same as the one used in the resource file, which was a string name. Thus the load will fail. A sure sign this happened is if this fails:

HRSRC hRes = FindResource(NULL, MAKEINTRESOURCE(MY_ID), _T("MYDATA"));

but this works:

HRSRC hRes = FindResource(NULL, _T("MY_ID"), _T("MYDATA"));

If you find this is the case, make sure your .rc file and your C/C++ code are using the same macro for your resource identifier. It can't just be the same "name". It has to be the same macro. If the macro is not available to the resource compiler it will use the name as a string, which is usually not what you want.

Best of luck.

Upvotes: 4

egur
egur

Reputation: 7980

2 things:

  • MAKEINTRESOURCE(RT_RCDATA) should be RT_RCDATA according to the docs.

  • The first parameter is the handle to the binary (DLL/exe) holding the resource, NULL implies the executable.

Upvotes: 2

Related Questions