C / C++ / MFC

25-Dec-06 19:04

Thank you so much perterchen, Now I will sit on work on your explanation Smile | :)

. Thanks a lot Smile | :)

Astricks26-Dec-06 2:27

26-Dec-06 2:27

Your example was so nice, realy useful. thanks a lot man. And I tried another simple thing, but why do I get this error peter?

template<class T> class Key
{
    T k;
    T* kptr;
    int length;
public:
    Key(T);
    // ...
};

void main()
{
Key < int > i;
}

: error C2512: 'Key<int>' : no appropriate default constructor available

peterchen26-Dec-06 2:38

peterchen

26-Dec-06 2:38

If a coworker asked me that, I'd start with a "questions" game: What does the compiler say? Where does it saay that? etc. - you could work this out yourself Wink | ;)

since you declare Key(T), the default constructor Key() is not generated automatically.

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Astricks26-Dec-06 2:46

26-Dec-06 2:46

oops, just a simple mistake. I'm taking up templates with an assumption it's too difficult to understand. So any error it throws look big for me . Sorry peter, it's the usual "no definition" error. Damn, I should have put Key(T){}. Now I defined it inline. Sorry for the stupid question. And Btw, next time if I come up with a good question would you try to extend your support? please?

peterchen26-Dec-06 3:15

peterchen

26-Dec-06 3:15

No problem Smile | :)

I just want to encourage you to help yourself.

Astricks wrote:
And Btw, next time if I come up with a good question would you try to extend your support? please?

No promise, but you aren't on a black list or something Wink | ;)

Astricks26-Dec-06 5:27

Weird C4244 warning message

26-Dec-06 5:27

peterchen wrote:
No problem I just want to encourage you to help yourself.

Thanks peter Smile | :)

peterchen wrote:
you aren't on a black list or something

pheww!

Cristian Amarie25-Dec-06 5:24

25-Dec-06 5:24

Environment:
Windows XP Professional 32-bit
Visual Studio C++ Express Edition 8.0 SP2
Platform SDK Windows 2003 Server RC2
Project: C++, Windows 32-bit (x86), Debug, Unicode

<br />
Compiling...<br />
Dialog.cpp<br />
d:\lbm\bdm\dialog.cpp(43) : warning C4244: 'argument' : conversion from 'LONG' to 'LONG', possible loss of data<br />
[rest of compilation continues]<br />

The code triggering the warning message:

#ifdef _WIN64
    SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG_PTR)(wcDlgInfo->m_wcDlgProc));
#else
    SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG __w64)(wcDlgInfo->m_wcDlgProc));
#endif

Normally the line

SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG_PTR)(wcDlgInfo->m_wcDlgProc));

would suffice, but this also complains about the conversion of LONG_PTR to LONG, as if LONG_PTR is 64-bit:

Compiling...
Dialog.cpp
d:\lbm\bdm\dialog.cpp(47) : warning C4244: 'argument' : conversion from 'LONG_PTR' to 'LONG', possible loss of data

Any ideas why
- LONG_PTR is considered "larger" than LONG on 32-bit x86, and
- what means exactly the "conversion from LONG to LONG" warning message means, since _WIN64 is not defined?

Many thanks,
Cristian Amarie

Mark Salsbery25-Dec-06 6:32

25-Dec-06 6:32

I'm not sure about the error message, but...

Cristian Amarie wrote:
but this also complains about the conversion of LONG_PTR to LONG, as if LONG_PTR is 64-bit

A LONG_PTR IS a 64-bit value in a 64-bit build. That's the whole reason for the newer type. It's
a LONG but large enough to hold a pointer when pointers are 32-bit or 64-bit.

I'm not sure what a "LONG __w64" is, but this line...

SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG __w64)(wcDlgInfo->m_wcDlgProc));

...won't work on a 32-bit build because pointers are 32-bit therefore you need to pass a 32-bit
value. Sure, you can cast a 64-bit but it's going to be truncated to 32-bits.

Mark

Cristian Amarie25-Dec-06 7:16

25-Dec-06 7:16

[A LONG_PTR IS a 64-bit value in a 64-bit build]
True, but as I stated in environment, is a 32-bit build.

[I'm not sure what a "LONG __w64" is, but this line...]
(Microsoft Specific) Lets you mark variables, such that when you compile with /Wp64 the compiler will report any warnings that would be reported if you were compiling with a 64-bit compiler.

Is a "marker".

About the last part of message, true, but (LONG __w64) was on #else part of #ifdef _WIN64.

Mark Salsbery25-Dec-06 10:08

25-Dec-06 10:08

Hmm

What type is wcDlgInfo->m_wcDlgProc?

Cristian Amarie25-Dec-06 19:39

25-Dec-06 19:39

typedef LRESULT (CALLBACK *WCDLGPROC)(HWND, UINT, WPARAM, LPARAM);

m_wcDlgProc is a pointer (to a window procedure).

Mark Salsbery26-Dec-06 5:18

26-Dec-06 5:18

Yeah that's a good WTF WTF | :WTF:

This...

::SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG)(LONG_PTR)(wcDlgInfo->m_wcDlgProc));

..."fixes" it on VS2003.

I'd call that a bug, but every time I do, someone has a good reason for the behavior Smile | :)

Cristian Amarie26-Dec-06 6:12

26-Dec-06 6:12

Now that's a stretch (Dad to DeeDee - Dexter's Laboratory) Big Grin | :-D

Subtracting times - need a result including milliseconds

prasad_som25-Dec-06 22:06

prasad_som

25-Dec-06 22:06

Cristian Amarie wrote:
Normally the line

SetWindowLongPtr(hdlg, DLGWINDOWEXTRA, (LONG_PTR)(wcDlgInfo->m_wcDlgProc));

would suffice, but this also complains about the conversion of LONG_PTR to LONG, as if LONG_PTR is 64-bit:

I aggree with you. This should suffice. About warning, probably this could be issue with IDE.

Prasad
Notifier using ATL | Operator new[],delete[][^]

SWDevil25-Dec-06 5:11

SWDevil

25-Dec-06 5:11

Hello,

I have 2 times which I would like to subtract.
One time is a time that consists of hours, minutes, seconds and milliseconds. For instance 12:24:59.0.
and the other time is a timer which consists only of milliseconds, seconds and minutes (no hours). For instance: 4.52.300.

The problem is that I need to subtract the two times and get a result which also contains the difference in milliseconds (this is critical for the timer).
I tried converting both times to COleDateTime, then subtracting them but I don't get the result in Milliseconds, so I lose information.
By the way, I have both times in SYSTEMTIME format but is there a function that subtracts them?

Any other ideas?

Re: Subtracting times - need a result including milliseconds

prasad_som25-Dec-06 19:41

prasad_som

25-Dec-06 19:41

SWDevil wrote:
By the way, I have both times in SYSTEMTIME format but is there a function that subtracts them?

Convert SYSTEMTIME to FILETIME using SystemTimeToFileTime. Convert FILETIME to ULARGE_INTEGER and use it for artimetic operations.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Max. value of int type variable and unsigned int type variable

cy163@hotmail.com25-Dec-06 3:31

cy163@hotmail.com

25-Dec-06 3:31

I would like to use a vector to hold a large volume of data. So, I conducted a test with std::vector. However, the value of 'Sum' is 16677720, instead of 100, 000, 000. However, i can get the value 100, 000, 000 when declare 'Sum' as unsigned int type. Why? My pc has 32-bit bus address.

<br />
vector <float> DDD;<br />
<br />
DDD.reserve.((10000 * 10000)/2*6)<br />
<br />
float  x= (float)1;<br />
for(int i = 0; i < (10000 * 10000); i++)<br />
{<br />
   DDD.push_back(x);<br />
}<br />
float Sum = 0;<br />
for(int j = 0; j < (10000 * 10000); j++)<br />
{<br />
    Sum += DDD[j];<br />
}<br />

Re: Max. value of int type variable and unsigned int type variable

Mark Salsbery25-Dec-06 6:41

25-Dec-06 6:41

The problem is with using a float, not 32 bit integers.

Your floats only have a precision of 7 digits. If you must use a floating point value then at
least use a double Smile | :)

Tick count

includeh1025-Dec-06 2:17

includeh10

25-Dec-06 2:17

Which function similar to GetTickCount() to get time in us (1/1000 ms) level?

David Crow25-Dec-06 5:08

David Crow

25-Dec-06 5:08

You want microsecond (1/1000 msec) resolution? If so, that's not possible.

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Cristian Amarie25-Dec-06 5:27

25-Dec-06 5:27

GetSystemTime contains all up to milliseconds.

Mark Salsbery25-Dec-06 6:46

25-Dec-06 6:46

If your hardware supports it, there's QueryPerformanceFrequency[^] and
QueryPerformanceCounter[^]

You may want to research the performance issues with using these as well as the accuracy Smile | :)