C / C++ / MFC Discussion Boards

Michael Dunn27-Nov-05 16:11

27-Nov-05 16:11

Three things:
CreateFile() returns INVALID_HANDLE_VALUE on error, not NULL.
1024^4 does not mean "1024 to the forth power."
Why are you trying to allocate that much memory in the first place? It will never succeed.

--Mike--
Visual C++ MVP Cool | :cool:

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There is a saying in statistics that a million monkeys pounding on typewriters would eventually create a work of Shakespeare. Thanks to the Internet, we now know that this is not true.

-- modified at 22:12 Sunday 27th November, 2005

Re: Flush a file after reading it?

Bob Stanneveld27-Nov-05 22:27

Bob Stanneveld

27-Nov-05 22:27

Hello,

The problem is that your buffer is too small. Just as Micheal Dunn pointed out: 1024^4 doesn't do what you want. operator ^ is the XOR operator. The result is: 1028.

You should try the following:

// read until there is nothing more to read:
char pcBuf[1024] = {0}; // buffer
DWORD dwBytesRead = 0;
while( !ReadFile(bipFile, pcBuffer, 1024, &dwBytesRead, NULL )
{
    if( dwBytesRead < 1024 )
        break; // end of the file found
    // do something with buffer
}

// do something with last bytes read in buffer

Hope this helps.

Behind every great black man...
... is the police. - Conspiracy brother

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Re: Flush a file after reading it?

Michael Dunn27-Nov-05 16:15

Michael Dunn

27-Nov-05 16:15

Just FYI, flushing is only meaningful when writing to a file. If you're just reading, there's nothing to flush.
Calling Flush() probably had some other side effect (resetting the file pointer or something) that made your code appear to work.

--Mike--
Visual C++ MVP Cool | :cool:

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"Just because the box has 2 gigabytes of memory doesn't mean you get to use it all!"
-- Rico Mariani, CLR perf guy

Re: Flush a file after reading it?

Lord Kixdemp28-Nov-05 13:55

Lord Kixdemp

28-Nov-05 13:55

Thanks all! I'll take your advices! Wink | ;-)

But... I always thought ^ was exponent... And, is 102400 a lot? 102.4 KB... And I do it because one never knows how much bytes a file has... or is there a way to know? WTF | :WTF:

Thanks!

Lord Kixdemp
www.SulfurMidis.com
www.SulfurSoft.tk
[ftp://][http://][hotline://]tsfc.ath.cx

Re: Flush a file after reading it?

Michael Dunn16-Dec-05 10:22

Michael Dunn

16-Dec-05 10:22

^ is often used in a text environment (like message boards) to mean exponent, however in C it means bitwise XOR.
1024⁴ = 1099511627776, or 1.1 trillion bytes.
You can call GetFileSize() to get the length.

--Mike--
Visual C++ MVP Cool | :cool:

LINKS~! Ericahist | PimpFish | CP SearchBar v3.0 | C++ Forum FAQ
"Just because the box has 2 gigabytes of memory doesn't mean you get to use it all!"
-- Rico Mariani, CLR perf guy

Re: Flush a file after reading it?

Lord Kixdemp16-Dec-05 10:37

Lord Kixdemp

16-Dec-05 10:37

Huh?
The first post here uses ^ as exponent:

http://www.gidforums.com/t-7788.html[^]

What's the exponent operator then? Thanks! Wink | ;-)

Lord Kixdemp
www.SulfurMidis.com
www.SulfurSoft.tk
[ftp://][http://][hotline://]tsfc.ath.cx

Re: Flush a file after reading it?

Michael Dunn16-Dec-05 10:52

Michael Dunn

16-Dec-05 10:52

There is no exponentiation operator, you use the pow() function instead.

--Mike--
Visual C++ MVP Cool | :cool:

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Re: Flush a file after reading it?

Lord Kixdemp16-Dec-05 12:53

Lord Kixdemp

16-Dec-05 12:53

Oh... OK, thanks! Wink | ;-)

Lord Kixdemp
www.SulfurMidis.com
www.SulfurSoft.tk
[ftp://][http://][hotline://]tsfc.ath.cx

CWebBrowser2::Navigate

includeh1026-Nov-05 19:10

includeh10

26-Nov-05 19:10

the function
CWebBrowser2::Navigate(url)
displays an error message-box if url doesn't exist.

is there any idea to avoid (or do not display) the message-box?

includeh10

Re: CWebBrowser2::Navigate

Michael Dunn27-Nov-05 16:16

Michael Dunn

27-Nov-05 16:16

Handle the NavigateError event and set the Cancel param to VARIANT_TRUE.

--Mike--
Visual C++ MVP Cool | :cool:

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Shots do not hurt other players... yet

what is the use of the CImageIterator

blackeye200426-Nov-05 19:00

blackeye2004

26-Nov-05 19:00

what is the use of the CImageIterator

Re: what is the use of the CImageIterator

Johann Gerell26-Nov-05 23:34

Johann Gerell

26-Nov-05 23:34

Having absolutely no clue about what you're actually talking about, since you provide zero context to a complete non-question, I'd give this sound guess:

An abstrcation of iteration through the pixels of an image.

--
The Blog: Bits and Pieces

-- modified at 5:34 Sunday 27th November, 2005

Re: what is the use of the CImageIterator

blackeye200426-Nov-05 23:46

blackeye2004

26-Nov-05 23:46

I am sorry,I can't use English well.My mean is that there is a CImageIterator class in CxImage, and what's use of this class?

Re: what is the use of the CImageIterator

Johann Gerell27-Nov-05 5:49

Johann Gerell

27-Nov-05 5:49

Then my initial guess was correct. I've used CxImage extensively and know for a fact that CImageIterator iterates the pixels of a CxImage.

--
The Blog: Bits and Pieces

Re: what is the use of the CImageIterator

blackeye200427-Nov-05 14:56

blackeye2004

27-Nov-05 14:56

Thank you for your answer.. I have another question that how to display a gif picture by CxImage?

blackeye

error LNK2001: unresolved external symbol

Chintoo72326-Nov-05 18:03

Chintoo723

26-Nov-05 18:03

I often get "error LNK2001: unresolved external symbol" for _FunctionName@24,
what is this supposed to mean?

what does this notation _FunctionName@24 mean?

thanks!

Re: error LNK2001: unresolved external symbol

Garth J Lancaster26-Nov-05 18:39

Garth J Lancaster

26-Nov-05 18:39

Different compilers/vendors 'decorate' functions names with various schemes when they compile your code into object modules - this is commonly known as 'mangling'

In MSVC for example, its possible to decode the function name AND its parameters from looking at a mangled name. There is also, to make things worse, a difference in 'c' vs c++ name generation ...

That you get a LNK2001 error should be obvious - you have a call to that 'FunctionName' in your code and it cant be found in an object module's symbol/export table - maybe you're not linking against the right object/DLL or such

There are plenty of articles out there detailing how to fix this along with stdcall, cdecl discussions (search to find what I mean), I'm probably not the best person to give you a more in-depth reply than this ..

'g'

how to check if a local link exists?

includeh1026-Nov-05 17:53

includeh10

26-Nov-05 17:53

assume there is a link
<a href="file://c:/abc/xxx">

how to know if the file exists?

the link may not be a file, i.e.
xxx=open?param
or something else.

includeh10

-- modified at 23:53 Saturday 26th November, 2005

Re: how to check if a local link exists?

Chintoo72327-Nov-05 1:20

Chintoo723

27-Nov-05 1:20

local link or a remote link I dont think it matters. To check if a URI exists, try the XMLHTTPREQUEST object. See http://jibbering.com/2002/4/httprequest.html[^]

See "Does a URL exist?" section in this page.

thanks!

TAPI and CLI (Calling line identity)

Vaclav26-Nov-05 17:34

Vaclav

26-Nov-05 17:34

Can I program TAPI to detect CLI tones instead of DTMF tones?
Thanks for reading.

Vaclav

How to request a local file?

includeh1026-Nov-05 17:33

includeh10

26-Nov-05 17:33

with CHttpConnection, we can easily request for a web file by function OpenRequest();

is it possible to request a local file,
such as "file://c:/abc/index.htm"
by CHttpConnection::OpenRequest() or other VC functions ?

includeh10

-- modified at 23:54 Saturday 26th November, 2005

Re: How to request a local file?

Michael Dunn27-Nov-05 16:20

Michael Dunn

27-Nov-05 16:20

Using a URL with the file: protocol works when using WinInet directly; I'd imagine that it would work with the MFC wrappers too. Just make sure to get the syntax right - there is a difference between file:// and file:///
For more info, see http://blogs.msdn.com/freeassociations/archive/2005/05/19/420059.aspx[^]

--Mike--
Visual C++ MVP Cool | :cool:

about the CxImage

blackeye200426-Nov-05 16:07

blackeye2004

26-Nov-05 16:07

what the use of the CxImageIterator Class in CxImage library?

blackeye

How can a window in a dialog receive keyboard message?

sude26-Nov-05 15:49

sude

26-Nov-05 15:49

How can a window in a dialog receive keyboard message?

I create a window in a dialog.This window can show 3D drawing including rotation and can receive mouse message,but it can not receive keyboard message.

Please tell me why,Thank you for your answer.My code for create window is as follow.Maybe it need more parameter.

My program for create window is as follow:
R1=CRect(200, 7, 1000, 200);

// TODO: Add extra initialization here
m_pDisplay->Create( NULL, //CWnd default
NULL, //has no name
WS_CHILD|WS_CLIPSIBLINGS|WS_CLIPCHILDREN|WS_VISIBLE,
R1,
this, //this is the parent
u1);

sude

Re: How can a window in a dialog receive keyboard message?

includeh1026-Nov-05 18:00

includeh10

26-Nov-05 18:00

it can receive keyboard input if it gets focus (by SetFocus() function).

the window may need TABSTOP style or something else.

includeh10

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