C / C++ / MFC Discussion Boards

Re: function prototype and return type

Sonia Gupta1-Jun-07 1:09

Sonia Gupta

1-Jun-07 1:09

one more question
function signatures contains function return type , arguments and not the funciton name?

Re: function prototype and return type

CPallini1-Jun-07 2:06

CPallini

1-Jun-07 2:06

AFAIK the function name is part of the function signature.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: function prototype and return type

Sonia Gupta1-Jun-07 2:39

Sonia Gupta

1-Jun-07 2:39

So what's the difference between function signature and function prototyping?

Re: function prototype and return type

toxcct1-Jun-07 2:48

toxcct

1-Jun-07 2:48

the prototype is all you need to know to use a function (its name, what it gets as a parameter, and its return type).

the signature is what permits to overload a function, that is, the prototype without the returning type...

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

Re: function prototype and return type

CPallini1-Jun-07 2:52

CPallini

1-Jun-07 2:52

AFAIK they are synonims, though function signature is (perhaps) a more conceptual, abstract term. On the other hand a function prototype has a more practical evidence, because you can find it inside header files.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: function prototype and return type

David Crow1-Jun-07 3:29

David Crow

1-Jun-07 3:29

Nothing. The terms are used interchangeably.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

error LNK2019: unresolved external symbol

bankai1231-Jun-07 0:32

bankai123

1-Jun-07 0:32

Hi, I've recently opened a vc6 MFC project into vs2005 and let it do the conversions. The code would compile fine. Next I added a class called AviFile(Creating Movie from HBitmap on Codeproject) to the project which I assume is just using win32 API. However when I try to compile, I get his error message.

1>AviFile.obj : error LNK2019: unresolved external symbol _AVIFileInit@0 referenced in function "public: __thiscall CAviFile::CAviFile(char const *,unsigned long,unsigned long)" (??0CAviFile@@QAE@PBDKK@Z)<br />
1>AviFile.obj : error LNK2019: unresolved external symbol _AVIFileExit@0 referenced in function "public: __thiscall CAviFile::~CAviFile(void)" (??1CAviFile@@QAE@XZ)<br />
1>AviFile.obj : error LNK2019: unresolved external symbol _AVIFileRelease@4 referenced in function "private: void __thiscall CAviFile::ReleaseMemory(void)" (?ReleaseMemory@CAviFile@@AAEXXZ)<br />
...etc<br />

I think there's something wrong with the linker settings, but I can't quite figure it out. I've googled for possible solutions, but still no luck.

Does anyone have an idea?

Thanks

Re: error LNK2019: unresolved external symbol

toxcct1-Jun-07 0:37

toxcct

1-Jun-07 0:37

the compiler probably doesn't find the related .lib file into which those symbols are defined...

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

Re: error LNK2019: unresolved external symbol

Rajkumar R1-Jun-07 0:44

Rajkumar R

1-Jun-07 0:44

link it with Vfw32.lib.

Re: error LNK2019: unresolved external symbol

Naveen1-Jun-07 0:46

Naveen

1-Jun-07 0:46

specify the Vfw32.lib in the "object/library modules"( project settings->Link ) of your project settings.

nave

[OpenedFileFinder]

Re: error LNK2019: unresolved external symbol

bankai1231-Jun-07 1:02

bankai123

1-Jun-07 1:02

The AviFile class doesn't use the Vfw32.lib library, but uses vfw.h.

I'm using Visual Studio 2005, so would "object/library modules" be the Additional Library Directories?

Thanks

Re: error LNK2019: unresolved external symbol

Naveen1-Jun-07 1:08

Naveen

1-Jun-07 1:08

bankai123 wrote:
The AviFile class doesn't use the Vfw32.lib library, but uses vfw.h.

Vfw32.lib will be having the link information for that functions.

bankai123 wrote:
I'm using Visual Studio 2005

I dont have VS2005 now. How ever it is not Additional Library Directories.

nave

[OpenedFileFinder]

Re: error LNK2019: unresolved external symbol

Rajkumar R1-Jun-07 1:11

Rajkumar R

1-Jun-07 1:11

Hi,
you may included vfw.h so you didn't get compilation error.
you got link error, find the option for linking corresponding to your IDE,

VS2005 needs to add vfw32.lib to project-><name>property->configuation property->linker->Input->Additional Dependency field.

Re: error LNK2019: unresolved external symbol

bankai1231-Jun-07 1:18

bankai123

1-Jun-07 1:18

Thanks for that, that solution solved the linker problem.

Now I seem to get this error
LINK : fatal error LNK1104: cannot open file 'C:\Program.obj'

Is this a problem with my directory path I specified? Which was
C:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\Lib

Re: error LNK2019: unresolved external symbol

Rajkumar R1-Jun-07 1:30

Rajkumar R

1-Jun-07 1:30

when you add vfw32.lib does the field already had other libs, if so
donot put commas in between only spaces or add it using IDE as seperate entry.

also for long path having spaces c:/program files use "c:/program files"
include it in quotes

Best Regards

Re: error LNK2019: unresolved external symbol [modified]

bankai1231-Jun-07 1:39

bankai123

1-Jun-07 1:39

Thanks for the help! Laugh | :laugh:

I forgot the quotes, the directory path should be in Dos 8.3 format, am I correct? Oh well, thanks, all is working now.

-- modified at 7:58 Friday 1st June, 2007

Re: error LNK2019: unresolved external symbol

Cedric Moonen1-Jun-07 1:14

Cedric Moonen

1-Jun-07 1:14

bankai123 wrote:
The AviFile class doesn't use the Vfw32.lib library, but uses vfw.h.

The header file only contains the class declaration. From where do you think the implementation of the methods comes from ? Bingo, from the library file Wink | ;)

.

In visual studio 2005, go into "Project Properties" -> "Linker" -> "Input" and specify the library in "Additional Dependencies".

Cédric Moonen
Software developer

Charting control [v1.2]

Example help please

Y_Kaushik1-Jun-07 0:17

Y_Kaushik

1-Jun-07 0:17

Hi can any one give me example program (or some thing idea) for
uploading and downloading a file in VC++, i am using MySQL as
an back end.

I can open (BROWSE) but can not select the exact path of file
and i am also unable for uploading it to database.

If any body can...Please help me

Regard's
Kaushik

Re: Example help please

Jhony george1-Jun-07 1:06

Jhony george

1-Jun-07 1:06

hai kaushik,

you refer this follwing link,
for downloading file and save into ur system.

http://www.codeguru.com/cpp/i-n/internet/filetransfer/article.php/c6235/[^]

Smile | :)

Re: Example help please

Hamid_RT1-Jun-07 1:26

Hamid_RT

1-Jun-07 1:26

Y_Kaushik wrote:
downloading a file in VC++,

See URLDownloadToFile function.

WhiteSky

Re: Example help please

David Crow1-Jun-07 3:33

David Crow

1-Jun-07 3:33

Y_Kaushik wrote:
can any one give me example program (or some thing idea) for
uploading and downloading a file in VC++...

From/to where?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

How to control Controls' Enter Event?

Peter, Chan1-Jun-07 0:15

Peter, Chan

1-Jun-07 0:15

I add a button on a dialog form. When the butter is on focus,I pressed the "Enter Key", the click event will be invoked. But if I set button's style "Owner draw", the click event will not be invoked when I pressed "Enter".
Could anyone give me the answer. Why?

Not only button, edit and some other controls seem very strange.

Re: How to control Controls' Enter Event?

Naveen1-Jun-07 1:04

Naveen

1-Jun-07 1:04

The Enter key will be sent to your button only if your button return DLGC_DEFPUSHBUTTON as response to the WM_GETDLGCODE message. When the owner style is set, this value will not be returned by the button. So the solution is to overide th WM_GETDLGCODE message of the button and return the DLGC_DEFPUSHBUTTON in addition to the default values.

like

return CButton::OnGetDlgCode()|DLGC_DEFPUSHBUTTON ;

nave

[OpenedFileFinder]

Re: How to control Controls' Enter Event?

Peter, Chan3-Jun-07 17:05

Peter, Chan

3-Jun-07 17:05

But if I return DLGC_DEFPUSHBUTTON, I can not owner draw its background. Do you have any other better way to handle it.
Thanks a lot.

Re: How to control Controls' Enter Event?

Naveen3-Jun-07 18:06

Naveen

3-Jun-07 18:06

ok ok i missed one point. In addition to the above thing handle the BN_SETSTYLE message( you have to manully add it message map. Class wizrad will not show this message ).

in the mesasge map
ON_MESSAGE( BM_SETSTYLE, OnSetStyle )

The function

LRESULT ButtonEx::OnSetStyle( WPARAM wParam_i, LPARAM lParam_i )<br />
{<br />
        const int ODDBTN_BS_TYPEMASK = 0x0000000FL;<br />
        return DefWindowProc( BM_SETSTYLE, ( wParam_i & ~ODDBTN_BS_TYPEMASK ) | BS_OWNERDRAW, lParam_i );<br />
 }

nave

[OpenedFileFinder]

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.