C / C++ / MFC Discussion Boards

Re: C++ - Static templated method inside a class

CPallini31-Jan-18 21:20

CPallini

31-Jan-18 21:20

Yes, that's it. Template method definitions should be in header files.

Re: C++ - Static templated method inside a class

Richard MacCutchan31-Jan-18 21:48

Richard MacCutchan

31-Jan-18 21:48

phil.o wrote:
the translation unit concept

The only reason for creating header files is when you have a set of common definitions that need to be shared by multiple translation units. If you only have a single .cpp file then all the definitions can safely be put in there. The #include statement is recognised by the preprocessor which reads all the include files and creates a new text file containing all the included code followed by the user written C/C++ code, and passes that new composite to the actual compiler.

Re: C++ - Static templated method inside a class

phil.o1-Feb-18 3:20

phil.o

1-Feb-18 3:20

I have learnt it the hard way Smile | :)

This explains why everything was fine as far as the editor/IDE were concerned, and why the issue only occurred on the linking phase. That's quite confusing for a beginner.

"I'm neither for nor against, on the contrary." John Middle

Re: C++ - Static templated method inside a class

Richard MacCutchan1-Feb-18 4:08

Richard MacCutchan

1-Feb-18 4:08

phil.o wrote:
quite confusing for a beginner.

and sometimes for the rest of us.

Explorer

Fedrer31-Jan-18 0:12

Fedrer

31-Jan-18 0:12

Hello,
I want to create application like windows explorer. I think I can use builtin tree and builtin list view.

I think there are some interface IShellFolderTree or IShellFolderList. Can you please guide me with any example/article?

Re: Explorer

Richard MacCutchan31-Jan-18 0:49

Richard MacCutchan

31-Jan-18 0:49

See Getting Information About the Contents of a Folder (Windows)[^]. You can also use Google/Bing to do your own searches.

Re: Explorer

Jochen Arndt31-Jan-18 1:22

Jochen Arndt

31-Jan-18 1:22

The IShellFolder interface is mainly used to manage folders and provide data for clipboard and drag & drop. I suggest to start without using that and implement the tree and list views using standard API functions like FindFirstFileEx and FindNextFile which provide basic information like size, time stamps and attributes.

For additional info like icons and file types use SHGetFileInfo.

To get the owner name for a file or directory use GetNamedSecurityInfo and LookupAccountSid.

Solutions to resolve reparse points (links and mounts) can be found in the web (open with CreateFile with flags FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT and call DeviceIoControl with FSCTL_GET_REPARSE_POINT).

To use the IShellFolder interface you have to get the DesktopFolder and use that to bind to other folders:

C++

LPSHELLFOLDER pDesktopFolder;
::SHGetDesktopFolder(&pDesktopFolder);

LPSHELLFOLDER psfFolder = NULL;
LPITEMIDLIST pFolderPIDL = ::ILCreateFromPath(lpszPath);
HRESULT hRes = pDesktopFolder->BindToObject(
    pFolderPIDL,
    NULL,
    IID_IShellFolder,
    IID_PPV_ARGS(&psfFolder)
);

// Example to get the PIDL of a named file or folder within a folder
// This PIDL can then be used for other IShellFolder operations
LPITEMIDLIST pPIDL;
CString strName; // name within folder
hRes = psfFolder->ParseDisplayName(
    NULL,		 // no hWnd necessary when showing no dialog
    NULL,		 // no bind context
    strName.GetBuffer(), // non-const LPWSTR
    NULL,		 // no need to get number of parsed characters
    &pPIDL,		 // PIDL relative to the parsing folder
    NULL		 // attributes not used
);
strName.ReleaseBuffer();

// Releasing
::CoTaskMemFree(pPIDL);
psfFolder->Release();
::ILFree(pFolderPIDL);
pDesktopFolder->Release();

As you can see there are lot of tasks where some are quite complex.

Re: Explorer

Randor 31-Jan-18 5:26

Randor

31-Jan-18 5:26

Hi,

It's alot of work and you will need alot of COM[^] and shell expertise[^]. Have a look at the explorer clone by David Erceg:

Explorer++ is a small and fast file manager for Windows.[^]

It comes with full source code.[^]

Best Wishes,
-David Delaune

Size of a window

Anthony Appleyard29-Jan-18 5:05

Anthony Appleyard

29-Jan-18 5:05

HWND hWnd;

After that declaration, please, how can I find the total outside size of the current window including the window's frames and menu and any scroll bars etc, not only the window's available area for writing text and images in?

Re: Size of a window

OriginalGriff29-Jan-18 5:07

OriginalGriff

29-Jan-18 5:07

Once you have the window handle, you just call GetWindowRect[^]

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!

Re: Size of a window

Victor Nijegorodov29-Jan-18 10:49

Victor Nijegorodov

29-Jan-18 10:49

There are some window functions you can use: Window Functions (Windows)

Re: Size of a window

Anthony Appleyard31-Jan-18 5:56

Anthony Appleyard

31-Jan-18 5:56

Thanks.

SetWindowPos() sets up a window, and needs the desired total window size including borders and scroll bars etc.

Can I find easily the values of the needed total window size (say xj and yj) needed to set up a window whose image-and-text area (= client area) is xi * yi)?

Re: Size of a window

Richard MacCutchan31-Jan-18 6:05

Richard MacCutchan

31-Jan-18 6:05

Use GetWindowRect and GetClientRect to find those two values. The difference is the size of the frame portion. You can then calculate your required client size, add that to the frame sizes to get your new window size.

Class as a DLL

ForNow24-Jan-18 5:37

ForNow

24-Jan-18 5:37

Just read an article on using classes as a DLLs following the class a __declspec(dllimport/dllexport) is needed. I was just wondering how MFC does it. On my system the MFC code is located in MFC140.DLL now when I inherit a let’s say CDialog class I don’t specify __declspec(dllimport)
Thanks

Re: Class as a DLL

Richard MacCutchan24-Jan-18 6:51

Richard MacCutchan

24-Jan-18 6:51

ForNow wrote:
I don’t specify __declspec(dllimport)

No because that declaration will be in the header file. You should take a look at Creating and Using a Dynamic Link Library (C++)[^] for more information. Basically the project that creates the dll needs __declspec(dllexport) and every application the wants to use it needs __declspec(dllimport). This is usually controlled by a #define in the header that goes with the dll. If you create a DLL project in Visual Studio and select the "Export Symbols" checkbox, you get the following in the header:

C++

// The following ifdef block is the standard way of creating macros which make exporting 
// from a DLL simpler. All files within this DLL are compiled with the WIN32PROJECT2_EXPORTS
// symbol defined on the command line. This symbol should not be defined on any project
// that uses this DLL. This way any other project whose source files include this file see 
// WIN32PROJECT2_API functions as being imported from a DLL, whereas this DLL sees symbols
// defined with this macro as being exported.
#ifdef WIN32PROJECT2_EXPORTS
#define WIN32PROJECT2_API __declspec(dllexport)
#else
#define WIN32PROJECT2_API __declspec(dllimport)
#endif

// This class is exported from the Win32Project2.dll
class WIN32PROJECT2_API CWin32Project2 {
public:
	CWin32Project2(void);
	// TODO: add your methods here.
};

extern WIN32PROJECT2_API int nWin32Project2;

WIN32PROJECT2_API int fnWin32Project2(void);

Re: Class as a DLL

ForNow24-Jan-18 7:28

ForNow

24-Jan-18 7:28

Thanks I was just curious how MFC does it the code is in MFC140.DLL
and I don’t see any __declspec(import)
When I want to use CDialog

Also I assume when I follow theses steps in my .dll I’ll create a .lib

Thanks

Re: Class as a DLL

Richard MacCutchan24-Jan-18 7:51

Richard MacCutchan

24-Jan-18 7:51

The exported labels are not in the dll, as that means nothing to the compiler. They are in one of the header files somewhere in the MFC include folders. So if you find the definition of CDialog it will somehow be defined there.

Re: Class as a DLL

ForNow24-Jan-18 8:09

ForNow

24-Jan-18 8:09

FYI I did a dependency walker against MFC140.DLL and I got all the entry points N/A meaning without function names

Re: Class as a DLL

Richard MacCutchan24-Jan-18 9:06

Richard MacCutchan

24-Jan-18 9:06

Well they will be in there somewhere, but MFC/C++ names get mangled up and are not always easy to recognise. Be that as it may, if the entry points didn't exist then the dll would not be usable. I have not used MFC for many years so cannot actually check any of this. The key point is to ignore the dll and inspect the header files.

Re: Class as a DLL

leon de boer24-Jan-18 13:02

leon de boer

24-Jan-18 13:02

Exporting from a DLL Using __declspec(dllexport)[^]

Many export directives, such as ordinals, NONAME, and PRIVATE, can be made only in a .def file, and there is no way to specify these attributes without a .def file. However, using __declspec(dllexport) in addition to using a .def file does not cause build errors.

It's a protection scheme they are exported as privates or ordinals probably so they can avoid ANSI, MBCS, and Unicode issues on the call name.

In vino veritas

modified 25-Jan-18 0:07am.

Re: Class as a DLL

Victor Nijegorodov24-Jan-18 9:34

Victor Nijegorodov

24-Jan-18 9:34

just read about the Extension DLLs | Microsoft Docs

How to create a thread in C Android NDK

ptr_Electron22-Jan-18 3:47

ptr_Electron

22-Jan-18 3:47

My development environment is Eclipse C Android NDK

I want to create and run a Simple thread from a function

I am trying to use

pthread_create()

Can some one point me to a simple thread example C Android

What I tired and confusing for me is, what parms I need to pass to this function ?

JNIEXPORT void JNICALL
Java_org_testjni_android_Game_someFunction(JNIEnv * env, jobject  obj)
{

Re: How to create a thread in C Android NDK

Richard MacCutchan22-Jan-18 4:32

Richard MacCutchan

22-Jan-18 4:32

What does the first part of your question have to do with the second? What thread are you trying to create and run? What is the JNI function for?

Re: How to create a thread in C Android NDK

CPallini22-Jan-18 9:49

CPallini

22-Jan-18 9:49

As Richard pointed out, there (should be) no need to export to the Java environment the pthread_create function. Make a wrapper (with a simpler signature) for that and then export to Java (if you need to) such a wrapper.
As about pthread_create, its very man page[^] provides sample code.

Registry returning FILE_NOT_FOUND

Richard Andrew x6420-Jan-18 13:46

Richard Andrew x64

20-Jan-18 13:46

I'm using a class to work with the registry that I downloaded from an MSDN article. The problem is that whenever I go to read a string (REG_SZ), the RegGetValue call fails with ERROR_FILE_NOT_FOUND (#2).

In fact no matter what I've tried, it insists on returning that error. I've tried building the program for 64-bit as well as 32 - no difference. I've made sure that the key is being opened properly. That succeeds, but reading a string value does not. I'm now pulling my hair out.

Does anyone know why it's returning ERROR_FILE_NOT_FOUND?

This is the code that's calling RegGetValue:

inline std::wstring RegGetString(HKEY hKey, const std::wstring& subKey, const std::wstring& value)
{    
    //
    // Request the size of the string, in bytes
    //
    DWORD dataSize{};
    LONG retCode = ::RegGetValue(
        hKey,
        subKey.c_str(),
        value.c_str(),
        RRF_RT_REG_SZ,
        nullptr,
        nullptr,
        &dataSize);
    if (retCode != ERROR_SUCCESS)
    {
        throw RegistryError{ "Cannot read string from registry", retCode };
    }

These are the relevant values: hKey is HKEY_CURRENT_USER,
subKey is "Software\Microsoft\Windows\CurrentVersion\Run" The string is properly escaped.
and value is a REG_SZ entry.

The difficult we do right away...
...the impossible takes slightly longer.

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