Getting a value from C++ DLL call

[AlexTekeuf]

Hi everybody!

I'm a beginner in AHK and I'm trying to call an AHK script from C++ code using the AHK DLL.

I have this AHK script file "MyScript.ahk" :

Code: Select all

#NoEnv
SetBatchLines -1
ListLines Off
#NoTrayIcon	
 
MyVar:="test3"

And this C++ code :

Code: Select all

typedef int(*AhkDll)(wchar_t *, wchar_t *, wchar_t *);
typedef int(*AhkReady)();
typedef int(*AhkAssign)(wchar_t *, wchar_t *);
typedef wchar_t*(*AhkGetVar)(wchar_t *, UINT);

//...

wchar_t* l_sRes = NULL;

// Load AHK DLL file 
HINSTANCE l_hAutoHotKeyLibrary = LoadLibrary(_T("AutoHotkey.dll"));
if (l_hAutoHotKeyLibrary != NULL)
{
	// Get function pointer 
	AhkDll l_hAutoHotKeyDLL = (AhkDll)GetProcAddress(l_hAutoHotKeyLibrary, "ahkdll");
	AhkReady l_hAutoHotKeyReady = (AhkReady)GetProcAddress(l_hAutoHotKeyLibrary, "ahkReady");
	AhkAssign l_hAutoHotKeyAssign = (AhkAssign)GetProcAddress(l_hAutoHotKeyLibrary, "ahkassign");
	AhkGetVar l_hAutoHotKeyGetVar = (AhkGetVar)GetProcAddress(l_hAutoHotKeyLibrary, "ahkgetvar");

	if ((l_hAutoHotKeyDLL != NULL) && (l_hAutoHotKeyReady != NULL) && (l_hAutoHotKeyAssign != NULL) && (l_hAutoHotKeyGetVar != NULL))
	{
		l_hAutoHotKeyAssign(_T("MyVar"), _T("test1"));
		l_sRes = l_hAutoHotKeyGetVar(_T("MyVar"), 0); // l_sRes = NULL

		l_hAutoHotKeyDLL(_T("MyScript.ahk"), _T(""), _T(""));
		l_sRes = l_hAutoHotKeyGetVar(_T("MyVar"), 0);  // l_sRes = ""

		l_hAutoHotKeyAssign(_T("MyVar"), _T("test2"));
		l_sRes = l_hAutoHotKeyGetVar(_T("MyVar"), 0); // l_sRes = "test2"

		while (l_hAutoHotKeyReady())
			Sleep(50);
		l_sRes = l_hAutoHotKeyGetVar(_T("MyVar"), 0); // l_sRes = NULL
	}
}

You can see the results I get from the GetVar calls in the code comments.
These results are very strange, Does someone can explain me how it exactly works?
The thing I want to do is to get the value from the script (here, "test3") to use it into my C++ code.

Thanks,
Alex.

[HotKeyIt]

1. Your ahkdll script needs to be #Persistent
2. The value returned from the functions is not always a pointer to string! (see docs)
3. When function like ahkgetvar returns a pointer to string, you will need to copy its value if you want to keep it. Autohotkey uses the same variable/memory to return strings from these functions.

[AlexTekeuf]

Thanks HotKeyIt for your answer!

1. Making my script #Persistent did the trick! Now I get the "test3" result
2. 3. I thought it was never a pointer as I set the second parameter value to 0 (<=> no pointer)

Anyway, now that it is #Persistent, I have another problem.
When I call this macro function another time in my application, I get an exception error 0x091C3326 in AutoHotKey.dll
It seems like the preivous called script is not "ended" or something...

Thanks again,
Alex.

[HotKeyIt]

The pointer I meant is the returned value, ahkgetvar always returns a pointer to string (also the pointer to var is returned as string).

Can you show exactly what you do when you get exception?