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Re: Strange variations

Dan McCormick15-Feb-06 11:10

Dan McCormick

15-Feb-06 11:10

hint_54 wrote:
You mean this?

( ( End.Hi - Begin.Hi ) << 32 ) + ( End.Lo - Begin.Lo )

regards

hint_54

Well, not really... If ( End.Lo - Begin.Lo ) generates a 'borrow' condition, that condition is not propagated up to the ( End.Hi - Begin.Hi ).

The shift by 32 also won't work since you are shifting a 32-bit value by 32-bits. The compiler does not automatically promote this expression to 64-bits. The shift results in either 0 because all of the bits get shifted out of our 32-bit value or, if you are on an intel processor or intel clone (and aren't we all), it remains unchanged because the hardware performs a ( modulo 32 ) on the shift count and you end up shifting by 0 bits.

A fully general solution would be to use something like ULARGE_INTEGER[^]

<br />
ULARGE_INTEGER largeBegin;<br />
ULARGE_INTEGER largeEnd;<br />
ULARGE_INTEGER largeResult;<br />
<br />
largeBegin.LowPart  = Begin.Lo;<br />
largeBegin.HighPart = Begin.Hi;<br />
<br />
largeEnd.LowPart  = End.Lo;<br />
largeEnd.HighPart = End.Hi;<br />
<br />
largeResult.QuadPart = largeEnd.QuadPart - largeBegin.QuadPart;<br />
<br />
printf( "Delta = %u\n", largeResult.LowPart );<br />

Because we are computing time deltas that we know are much, much less than 2³², we can safely ignore largeResult.HighPart - it will always be 0. We just had to perform 64-bit math to handle those occasional 'borrow' conditions. If we were doing general math on arbitary values, then we couldn't just throw that value away.

Later,
Dan

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Format of data in writing file , on different Windows

zahid_ash14-Feb-06 8:14

zahid_ash

14-Feb-06 8:14

HI,

I am using the code below for writing in the file, that file opening on windows XP using WordPad , and the data is in new line for every \n but in win2k and XP 2003 server \n does not works and a box appears and all the data is written in one line.

Why it is so ?

CString write = res+",\t\t\t"+res1+"\n";

percentFile.Open( strFormulaPath , CFile::modeCreate|CFile::modeNoTruncate|CFile::modeReadWrite|CFile::typeBinary);

percentFile.Seek(0L,CFile::end);
percentFile.Write(write , write.GetLength ());
percentFile.Close ();

Regards.

Re: Format of data in writing file , on different Windows

Red Stateler14-Feb-06 8:57

Red Stateler

14-Feb-06 8:57

Use "\r\n" instead of just "\n"

Serial port interfacing

srija14-Feb-06 7:02

srija

14-Feb-06 7:02

am a novice in working with VC++,actually am working on sensor interfacing, could anybody help me with Port configuration of the serail port interfacing. After configuring the port by default parameters like baudrate,etc, i should send telegram code in HEX to sensor, but am getting an error message. I couldnt proceed further. I would appreciate, if anybody helps me out.

srija

Re: Serial port interfacing

Milton Karimbekallil14-Feb-06 8:16

Milton Karimbekallil

14-Feb-06 8:16

be more specific, then it will be easy to suggest a solution.
Which API call failed? whats the error code returned?
Use ::GetLastError() API to see the error code.

rgds...mil10

Re: Serial port interfacing

Dan McCormick14-Feb-06 8:29

Dan McCormick

14-Feb-06 8:29

What function (or method) is returning an error code to you and what is the error code?

Dan

Winsock2.h and "unresolved external error"

Mutty14-Feb-06 6:53

Mutty

14-Feb-06 6:53

I am trying to do this:

char szHostName[MAX_PATH];
gethostname(szHostName, MAX_PATH);

I have included winsock2.h yet am getting:

error LNK2019: unresolved external symbol __imp__gethostname@8

Anybody know what I am missing? VS2002

thanks, -mutty

Re: Winsock2.h and "unresolved external error"

James R. Twine14-Feb-06 6:57

James R. Twine

14-Feb-06 6:57

Sounds like you are not linking with the Winsock2 library (Ws2_32.lib).

Peace!

-=- James

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Re: Winsock2.h and "unresolved external error"

Mutty14-Feb-06 7:23

Mutty

14-Feb-06 7:23

thank you - how do I link WS2_32.lib?

Stupid - never mind this. I was trying to open the property pages for the SOLUTION, not the Project. No wonder there was no linker folder!

-mutty

-- modified at 13:42 Tuesday 14th February, 2006

Re: Winsock2.h and "unresolved external error"

ThatsAlok14-Feb-06 22:22

ThatsAlok

14-Feb-06 22:22

Mutty wrote:
thank you - how do I link WS2_32.lib?

#pragma comment(lib,"WS2_32.lib")

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Re: Winsock2.h and "unresolved external error"

David Crow14-Feb-06 7:00

David Crow

14-Feb-06 7:00

Mutty wrote:
I have included winsock2.h yet am getting:

error LNK2019: unresolved external symbol __imp__gethostname@8

Linker errors and header files (usually) have nothing to do with each other. Had it been a header-related issue, you would have most likely seen a compiler error.

"The greatest good you can do for another is not just to share your riches but to reveal to him his own." - Benjamin Disraeli

inlining problem

hint_5414-Feb-06 6:21

hint_54

14-Feb-06 6:21

I've tryed the following code.

// somefile.h
class MyClass {
public:
inline void MemberFunction( void );
};

// somefile.cpp
#include "somefile.h"
void MyClass::MemberFunction( void ) // Also tryed "inline void MyClass::Memb..."
{
// Blá, blá, blá...
}

// Launcher.cpp
#include "somefile.h"
int main( void )
{
MyClass Example;
Example.MemberFunction();
return 0;
}

#ENDCODE

But I get

launcher.obj : error LNK2001: unresolved external symbol "public: void __thiscall CCPU::SomeFunction(void)" (?SomeFunction@CCPU@@QAEXXZ)
Debug/LOAC.exe : fatal error LNK1120: 1 unresolved externals

Any suggestions?

regards

hint_54

Re: inlining problem

C^hris L^osinger14-Feb-06 6:33

C^hris L^osinger

14-Feb-06 6:33

is somefile.cpp part of the project?
is SomeFunction the same as MemberFunction?

Cleek | Image Toolkits | Thumbnail maker

Re: inlining problem

hint_5414-Feb-06 6:36

hint_54

14-Feb-06 6:36

Yes, the file is part of the project and functions are the same (my mistake on that one Big Grin | :-D

)

regards

hint_54

Re: inlining problem

James R. Twine14-Feb-06 6:36

James R. Twine

14-Feb-06 6:36

The error is complaining about member SomeFunction() in class CCPU, but you show code from MyClass...?

Peace!

-=- James

Re: inlining problem

hint_5414-Feb-06 6:38

hint_54

14-Feb-06 6:38

It was an example. I'm having this problem on several classes/member functions, so I decided to pull off the error message with a "SomeFunction()" function and post an example with sample names.

regards

hint_54

Re: inlining problem

James R. Twine14-Feb-06 6:40

James R. Twine

14-Feb-06 6:40

   Only if you are sure that the code sample you posted is also generating the error...

   Is the class' CPP file included in the project? Do things work correctly if you put the implementation of the function into the .H file?

   Peace!

-=- James

Re: inlining problem

hint_5414-Feb-06 6:46

hint_54

14-Feb-06 6:46

James R. Twine wrote:
Only if you are sure that the code sample you posted is also generating the error...

Yes, it is.

James R. Twine wrote:
Is the class' CPP file included in the project?

Yes, it is.

James R. Twine wrote:
Do things work correctly if you put the implementation of the function into the .H file?

Actually, they do. Even with the "inline" keyword. But if I don't use "inline" it works well in different files.

regards

hint_54

Re: inlining problem

James R. Twine14-Feb-06 7:02

James R. Twine

14-Feb-06 7:02

OK - something about inline functions needing to have their implementation be in the .H file comes to mind (after the class dec.), but I cannot find anything about it in the MSDN collection. I remember that this was a bug in VC++ 6.0 or something like that?

Peace!

-=- James

Re: inlining problem

hint_5414-Feb-06 7:04

hint_54

14-Feb-06 7:04

James R. Twine wrote:
I remember that this was a bug in VC++ 6.0 or something like that?

Well, Could be... I'm using VC++ 6 Big Grin | :-D

regards

hint_54

Re: inlining problem

David Crow14-Feb-06 6:58

David Crow

14-Feb-06 6:58

Inline functions are not visible outside of the source file where they are defined. This is why you seem then declared in the same file, usually at the bottom, in which they are defined.

"The greatest good you can do for another is not just to share your riches but to reveal to him his own." - Benjamin Disraeli

Re: inlining problem

hint_5414-Feb-06 6:58

hint_54

14-Feb-06 6:58

Like templates, right? I see.

Thx

hint_54

Good Book for "advanced beginners" C++

ldsdbomber14-Feb-06 5:57

ldsdbomber

14-Feb-06 5:57

I'm looking for a good book to re-learn programming (in C++). I have Stroustrup but I have the feeling this will be more useful to me once I'm comfortable again. I've been away from programming for at least 4 years and only really learned "on the job" (tools programming windows dialog based apps), but would like to build a more solid foundation this time. I also have Eckels book but again this doesn't seem to be the kind of thing I'm after (though it's excellent on its own merits). I just wondered if there was a good "one book" answer to getting me started with the basics, including setting up compiling and linking properly (and understanding it!), and then building knowledge of the language and libraries etc in a structured, easy to follow way.
thanks in advance.

Re: Good Book for "advanced beginners" C++

David Crow14-Feb-06 6:48

David Crow

14-Feb-06 6:48

ldsdbomber wrote:

I'm looking for a good book to re-learn programming (in C++).

Since you asked a C++ question in a VC++ forum, which is it that you are ultimately after?

"The greatest good you can do for another is not just to share your riches but to reveal to him his own." - Benjamin Disraeli

Re: Good Book for "advanced beginners" C++

Ed K14-Feb-06 7:05

Ed K

14-Feb-06 7:05

You are in rare form today!

DavidCrow wrote:
Since you asked a C++ question in a VC++ forum, which is it that you are ultimately after?

Other than the C++/CLI forum wouldn't this be the place?

ed

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