Re: Template ? - C / C++ / MFC Discussion Boards

Stan the man10-Jan-03 15:24

10-Jan-03 15:24

Hi. This is a continuation of the ? before. I just can't seem to compile the program.

I had a program with CClass and CBaseClass classes DONE without Template and it works fine. Now I changed things to:

template<class x=""> CBaseClass
{
...
}

Outside the template the functions are in..

template<class x=""> void CBaseClass<x>::Function()
{
...
}

I know the base baseclass declaration is OK

AND

template<class x=""> CClass: public CBaseClass<x>
{
//I tried several syntax for the constructor and other fuunctions

CClass();
virtual ~CClass();

OR

CClass():CBaseClass<x>();
virtual ~CClass():CBaseClass<x>();

void Function():CClass<x>::Function()

//Both don't work

}

Outside the template the functions are in..

template<class x=""> CClass<x>::CClass()
{

}

...

Now because everything worked before, and I only added the syntax for the template, I know that it must be the syntax or something.

The compiler error is:
error LNK2001: unresolved external symbol ...

What I really need is exactly what the syntax needs to be. I can't find this anywhere at the moment. What I changed seemed very straight forward.

Appreciate any help to clearing this syntax up. Thanks!!

Re: Template ?

Michael Dunn10-Jan-03 15:41

Michael Dunn

10-Jan-03 15:41

Please repost and check the Display this message as-is (no HTML) box so your template params show up properly.

--Mike--
I'm bored... Episode I bored.
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Re: Template ?

Stan the man10-Jan-03 23:51

Stan the man

10-Jan-03 23:51

OK. This is the second try.

I had a program with CClass and CBaseClass classes DONE without Template and it works fine. Now I changed things to:

template<class X> CBaseClass
{
...
}

Outside the template the functions are in..

template<class X> void CBaseClass<X>::Function()
{
...
}

I know the base baseclass declaration is OK

AND

template<class X> CClass: public CBaseClass<X>
{
//I tried several syntax for the constructor and other fuunctions

CClass();
virtual ~CClass();

OR

CClass():CBaseClass<X>();
virtual ~CClass():CBaseClass<X>();

void Function():CClass::Function<X>()

//Both don't work

}

Outside the template the functions are in..

template<class X> CClass<X>::CClass()
{

}

...

Now because everything worked before, and I only added the syntax for the template, I know that it must be the syntax or something.

The compiler error is:
error LNK2001: unresolved external symbol ...

What I really need is exactly what the syntax needs to be. I can't find this anywhere at the moment. What I changed seemed very straight forward.

Re: Template ?

Michael Dunn11-Jan-03 6:14

Michael Dunn

11-Jan-03 6:14

template <class X> class CBaseClass
{
};

template <class X> class CClass : public CBaseClass<X>
{
CClass();
virtual ~CClass();

void Function();
};

template <class X>
CClass<X>::CClass() : CBaseClass<X>()
{ }

template <class X>
CClass<X>::~CClass()
{ }

template <class X>
void CClass<X>::Function()
{ }

Re: Template ?

Stan the man11-Jan-03 14:31

Stan the man

11-Jan-03 14:31

Hi Michael.

Thanks for the patience and help thus far.

From what I can see, only the template declaration and the Constructor for the derived class has different syntax. The others look normal template syntax. I tried this but am getting:

error LNK2001: unresolved external symbol "public: virtual __thiscall CTCRSSRecoilCoilReport<class CCircBufferT<float,struct _DATA_STRUCTURE_> >::~CTCRSSRecoilCoilReport<class CCircBufferT<float,struct _DATA_STRUCTURE_> >(void)" (?
?1?$CTCRSSRecoilCoilReport@V?$CCircBufferT@MU_DATA_STRUCTURE_@@@@@@UAE@XZ)

error LNK2001: unresolved external symbol "public: virtual void __thiscall CTCRSSRecoilCoilReport<class CCircBufferT<float,struct _DATA_STRUCTURE_> >::EndCoilReport(class CString,struct _RECOILING_COIL_REPORT_HOLDER_ *)" (?EndCoilR
eport@?$CTCRSSRecoilCoilReport@V?$CCircBufferT@MU_DATA_STRUCTURE_@@@@@@UAEXVCString@@PAU_RECOILING_COIL_REPORT_HOLDER_@@@Z)

error LNK2001: unresolved external symbol "public: __thiscall CTCRSSRecoilCoilReport<class CCircBufferT<float,struct _DATA_STRUCTURE_> >::CTCRSSRecoilCoilReport<class CCircBufferT<float,struct _DATA_STRUCTURE_> >(void)" (??0?$CTCRS
SRecoilCoilReport@V?$CCircBufferT@MU_DATA_STRUCTURE_@@@@@@QAE@XZ)

...

from the locations where I am calling the classes. I am not sue what this means unless the way you call it is different then normal template calling (Which is different only in declaration).

I am not sure what the Link 2001 error means. I know that the program did work right before. It seems like the program is getting errors from just calling the classes so I must not be declaring things right somewhere.

Thanks.

Re: Template ?

Michael Dunn11-Jan-03 19:26

Michael Dunn

11-Jan-03 19:26

See Why do I get a link error when compiling my templates?[^]

The code for all template classes and methods has to be in header files so it's available to all translation units (CPP files), same as inline functions.

--Mike--
I'm bored... Episode I bored.
1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click!
My really out-of-date homepage
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Re: Template ?

Stan the man12-Jan-03 4:19

Stan the man

12-Jan-03 4:19

Hi Micheal. Thanks. I will try this.

Re: Template ?

Stan the man12-Jan-03 4:48

Stan the man

12-Jan-03 4:48

Hi Michael.

I tried this. I ended PUT ALL the functions insides the template itself all in the header file. But it is still the same Link 2001 unresolved external symbol error. I can't understand it. I never had to put all the functions in the template in the heade file if it is not derived from it. It works fine.

I am really confused now as to what is actually the problem. It must be syntax. Right now I just want to change it to this class and its derived class to a template. I am not actually using the <class X> part yet meaning it should still work as before without the template declarations.

Any other ideas? Appreciate your help through this

Every build destroys my gif resource

georgiek5010-Jan-03 13:51

georgiek50

10-Jan-03 13:51

I include a gif resource into my project but every time I build it the gif becomes 0 kb and when I try to view it in windows it says no preview available. I am using MS VC++ 6.0 w/ service pack 5. Anyone else with this problem?

questions , questions.....

joshfl10-Jan-03 12:56

joshfl

10-Jan-03 12:56

http://www.wintellect.com/forum/topic.asp?TOPIC_ID=1132

so im creating this System Wide Keyboard Hooking Function, and i thought it would catch everything , but this group is having a discussion about it, and one says a SWKH will not catch a Ctrl-Alt-Delete, is that true??

todo....
:: insert inpirational text here ::

Re: questions , questions.....

Michael Dunn10-Jan-03 13:44

Michael Dunn

10-Jan-03 13:44

Of course not. The whole point of C+A+D is that it's secure - when you press it, only the OS responds to it.

--Mike--
I'm bored... Episode I bored.
1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click!
My really out-of-date homepage
Sonork-100.19012 Acid_Helm

Re: questions , questions.....

Joan M12-Jan-03 21:47

Joan M

12-Jan-03 21:47

Believe me:

if you want to catch Ctrl+Alt+Del you must do one of this things:

1. Create a Gina DLL.
2. Get a Gina DLL from somewhere.

the reason is clear:
In order to be secure its forbidden to get acces directly from an app to the Login part of the OS.
You've got to do it via a GINA that must be installed in the OS copying it somewhere and giving it's right path in the registry.
Take a look at the MSDN in order to find out more.

hope this helps...

unique id...

User 988510-Jan-03 12:16

User 9885

10-Jan-03 12:16

I want a standard C++ way to generate a unique id. Is there a way, I can do it without using Windows API or MFC - just C++ and STL.

If you guys know anyway to do this, please let me know. Thanks.

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

Re: unique id...

C^hris L^osinger10-Jan-03 20:28

C^hris L^osinger

10-Jan-03 20:28

this could work:

srand(time());
short id[numBytes / 2];
for (int i=0;i < numBytes / 2;i++)
{
  id[i] = rand();
}

as long as numBytes is sufficiently long, you'll probably never repeat an ID.

or, try : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcedcom/htm/cerefcocreateguid.asp[^]

I'm not the droid you're looking for.

ThumbNailer

Fun with std::map

Chris Richardson10-Jan-03 11:21

Chris Richardson

10-Jan-03 11:21

Hey guys,

I'm having some trouble with a std::map object I'm trying to use. Can any STL guys out there see something I'm doing wrong in my code. I've been debugging this for a couple hours now, stepping through STL code (which isn't fun!).

All I'm trying to do is associate a structure with a string. So, I insert a value_type with a string and a structure, then I try to look up the exact same string, and I get an invalid iterator. One wierd thing, is that it works perfectly for the first item I insert. Looking at the guts of the tree, I can see that the second object is there, it just checks the wrong side of the tree when it goes to look it up Confused | :confused:

// Some definitions...
typedef basic_string<TCHAR> CTCharString;
struct CTCharStringLess : public binary_function<CTCharString, CTCharString, bool>
{
    bool operator()(const CTCharString& x, const CTCharString& y) const
    {
      return _tcscmp( x.c_str(), y.c_str() );
    }
};

typedef struct tagFoo
{
   long Bar;
}Foo;

typedef map<CTCharString,Foo,CTCharStringLess> CStdMapStringToStruct;

// Inside the code
CStdMapStringToStruct MyMap;
Foo stMyStruct;
 
// Insert the first item.
MyMap.insert( CStdMapStringToStruct::value_type( _T("dummy_item", stMyStruct ) );
 
// This line finds the correct item.
CStdMapStringToStruct::iterator oIter = MyMap.find( _T("dummy_item") );
 
// Insert a second item.
MyMap.insert( CStdMapStringToStruct::value_type( _T("dummy_item_2"), stMyStruct ) );
 
// Why doesn't this line find the item????
oIter = MyMap.find( _T("dummy_item_2") );

Thanks,

Chris Richardson

Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

Re: Fun with std::map

AlexO10-Jan-03 11:34

AlexO

10-Jan-03 11:34

i suspect :

return _tcscmp( x.c_str(), y.c_str() );

should be
return _tcscmp( x.c_str(), y.c_str() ) < 0;

Re: Fun with std::map

Chris Richardson10-Jan-03 11:42

Chris Richardson

10-Jan-03 11:42

Wow, do I feel like a dummy. Of course, your suggestion works perfectly.

Thanks!

Chris Richardson

Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

System Wide Keyboard Hooking

joshfl10-Jan-03 10:31

joshfl

10-Jan-03 10:31

Hey all, me again Smile | :)

i started a new thread because (thanks to all the cpians) i figured out the initial parts of the app i needed, and now its onto the next issue I have Smile | :)

to keep people from exiting my app , i need to disable all the ctrl-alt-delete , altf4 stuff, and the ::pretranslatemessage stuff is not quite robust enough for me Smile | :)

so apparently i need to create a system wide keyboard hook.....

i have no idea how to start.

please help Smile | :)

josh

todo....
:: insert inpirational text here ::

Re: System Wide Keyboard Hooking

Joan M10-Jan-03 10:48

Joan M

10-Jan-03 10:48

System Wide KH only can be in a DLL so...

STEPS:
1. You must create a DLL.
2. Declare a static callback function:

static LRESULT CALLBACK HookTeclatLL(int nCode,WPARAM wParam,LPARAM lParam);

3. Create a f(x) that you'll export in order to start/stop that hook depending on a boolean parameter:

Setting the hook:hHookTeclat = SetWindowsHookEx(WH_KEYBOARD_LL, HookTeclatLL, hInstDLLSCT, NULL);

Unhooking:
if(hHookTeclat != NULL)
{
  UnhookWindowsHookEx(hHookTeclat);
  return true;
}

4. in the static callback f(x)...

static LRESULT CALLBACK HookTeclatLL(int nCode,WPARAM wParam,LPARAM lParam)
{
	if (nCode == HC_ACTION)
  {
		switch (wParam)
    {
			case WM_KEYDOWN:
      case WM_SYSKEYDOWN:
      case WM_KEYUP:
      case WM_SYSKEYUP:
			{
				LPKBDLLHOOKSTRUCT p = (LPKBDLLHOOKSTRUCT)lParam;
				bool bEliminarPressioTecla = false;

				// Paquet de tecles independents (hi hagi o no apretat ALT/Ctrl... s'eliminen de la cua de pressions de tecles).
				bEliminarPressioTecla =	((p->vkCode == VK_RWIN) ||
																(p->vkCode == VK_LWIN) ||
																(p->vkCode == VK_ESCAPE) ||
																(p->vkCode == VK_F1) || 
																(p->vkCode == VK_F2) || 
																(p->vkCode == VK_F3) || 
																(p->vkCode == VK_F4) || 
																(p->vkCode == VK_F5) || 
																(p->vkCode == VK_F6) || 
																(p->vkCode == VK_F7) || 
																(p->vkCode == VK_F8) || 
																(p->vkCode == VK_F9) || 
																(p->vkCode == VK_F10) || 
																(p->vkCode == VK_F11) || 
																(p->vkCode == VK_F12) || 
																(p->vkCode == VK_CANCEL) ||
																(p->vkCode == VK_RBUTTON) || 
																(p->vkCode == VK_PAUSE) ||
																(p->vkCode == VK_SNAPSHOT) ||
																(p->vkCode == VK_APPS) ||
																(p->vkCode == VK_SCROLL));

					// En cas que no s'hagi eliminat la tecla fins ara...
				if (!bEliminarPressioTecla)
				{
					// Paquet de tecles amb combinació amb ALT.
					if ((p->flags & LLKHF_ALTDOWN) != 0)
					{
						bEliminarPressioTecla = (p->vkCode == VK_TAB);
					}

					if ((p->flags & MOD_WIN) != 0)
					{
						bEliminarPressioTecla = true;
					}
				}

				if (bEliminarPressioTecla) 
				{
					return 1; IMPORTANT! in order to avoid that keystroke to be used...
				}

				break;
			}
		}
	}

	return CallNextHookEx(hHookTeclat, nCode, wParam, lParam);
}

I didn't wanted to format all that code... copy it and examine it outside the web page...

Hope this helps...

I'll go to sleep...

Re: System Wide Keyboard Hooking

joshfl10-Jan-03 11:19

joshfl

10-Jan-03 11:19

i just left work so i cannot check the code out til i get home, but it looks like a pretty straight forward guide Smile | :)

Thanks!

todo....
:: insert inpirational text here ::

Re: System Wide Keyboard Hooking

joshfl10-Jan-03 12:47

joshfl

10-Jan-03 12:47

static LRESULT CALLBACK HookTeclatLL(int nCode,WPARAM wParam,LPARAM lParam)
{
if (nCode == HC_ACTION)
{
switch (wParam)
{

case WM_KEYDOWN:
case WM_SYSKEYDOWN:
case WM_KEYUP:
case WM_SYSKEYUP:
{
LPKBDLLHOOKSTRUCT p = (LPKBDLLHOOKSTRUCT)lParam;
bool bEliminarPressioTecla = false;

// Paquet de tecles independents (hi hagi o no apretat ALT/Ctrl... s'eliminen de la cua de pressions de tecles).
bEliminarPressioTecla = ((p->vkCode == VK_RWIN) ||
(p->vkCode == VK_LWIN) ||
(p->vkCode == VK_ESCAPE) ||
(p->vkCode == VK_F1) ||
(p->vkCode == VK_F2) ||
(p->vkCode == VK_F3) ||
(p->vkCode == VK_F4) ||
(p->vkCode == VK_F5) ||
(p->vkCode == VK_F6) ||
(p->vkCode == VK_F7) ||
(p->vkCode == VK_F8) ||
(p->vkCode == VK_F9) ||
(p->vkCode == VK_F10) ||
(p->vkCode == VK_F11) ||
(p->vkCode == VK_F12) ||
(p->vkCode == VK_CANCEL) ||
(p->vkCode == VK_RBUTTON) ||
(p->vkCode == VK_PAUSE) ||
(p->vkCode == VK_SNAPSHOT) ||
(p->vkCode == VK_APPS) ||
(p->vkCode == VK_SCROLL));

// En cas que no s'hagi eliminat la tecla fins ara...
if (!bEliminarPressioTecla)
{
// Paquet de tecles amb combinació amb ALT.
if ((p->flags & LLKHF_ALTDOWN) != 0)
{
bEliminarPressioTecla = (p->vkCode == VK_TAB);
}

if ((p->flags & MOD_WIN) != 0)
{
bEliminarPressioTecla = true;
}
}

if (bEliminarPressioTecla)
{
return 1; IMPORTANT! in order to avoid that keystroke to be used...
}
break;
}
}
}
return CallNextHookEx(hHookTeclat, nCode, wParam, lParam);
}

Deleting intermediate files and output files for project 'swkh - Win32 Debug'.
--------------------Configuration: swkh - Win32 Debug--------------------
Compiling...
swkh.cpp
c:\windows\desktop\visualstudio6\myprojects\swkh\swkh.cpp(1) : error C2146: syntax error : missing ';' before identifier 'CALLBACK'
c:\windows\desktop\visualstudio6\myprojects\swkh\swkh.cpp(1) : fatal error C1004: unexpected end of file found
Error executing cl.exe.

swkh.dll - 2 error(s), 0 warning(s)

todo....
:: insert inpirational text here ::

Re: System Wide Keyboard Hooking

Joan M12-Jan-03 21:41

Joan M

12-Jan-03 21:41

I've ommitted one thing... Blush | :O

you've to change those lines in stdafx.h (comment the first one as in the sample and add the second one...):

//#define WIN32_LEAN_AND_MEAN		// Exclude rarely-used stuff from Windows headers
#define _WIN32_WINNT 0x0400

Re: System Wide Keyboard Hooking

joshfl13-Jan-03 5:35

joshfl

13-Jan-03 5:35

Thank You Joan Murt, youve been extremely helpful for me.

if (bEliminarPressioTecla)
{
return 1; IMPORTANT! in order to avoid that keystroke to be used...
}
break;
}
}

I also forgot to comment that part Smile | :)

Im going to try to build this .dll later today, i got a few other duties to perform first Smile | :)

ill let you know how it goes....

todo....
:: insert inpirational text here ::

setting/reading values of vars whe I have only the name of the var.

Joan M10-Jan-03 9:38

Joan M

10-Jan-03 9:38

Hello,

I have the name of a variable, let's call it "iCounter", is there any way to set a value to a var when I got only its name?

Sample of what I means:

CString csNameOfVar = "iCounter";

GetTheAdressOfAVarWiththisName(csNameOfvar) = Value_that_I_Must_set;

Does a function that acts as "GetTheAdressOfAVarWiththisName" exists?

thank you in advance.

Re: setting/reading values of vars whe I have only the name of the var.

Maximilien10-Jan-03 9:58

Maximilien

10-Jan-03 9:58

That would be fun, but I don't think so... C++ is not symbolic!

but,

One way of doing it, would be to add your variable into a map with the name of the variable as the key; but maybe not!?!?!

Max,

Last Visit: 31-Dec-99 18:00 Last Update: 26-Sep-24 15:27

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