C / C++ / MFC

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.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Cristian Amarie25-Dec-06 5:27

Cristian Amarie

25-Dec-06 5:27

GetSystemTime contains all up to milliseconds.

Mark Salsbery25-Dec-06 6:46

Mark Salsbery

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 | :)

includeh1025-Dec-06 7:20

A Problem with CStdioFile

25-Dec-06 7:20

great!
QueryPerformanceCounter() works perfect!

It is really impossible if you are not good enough.

yaros2125-Dec-06 0:10

yaros21

25-Dec-06 0:10

Hello!
I use Visual Studio 2005 SP 1. Here it a part of my code:

CStdioFile fd;
CString t;
fd.Open(_T("rep.txt"), CFile::modeRead, 0);
fd.ReadString(t);

This file contains the russian language and when I use debugger I see that 't' contains is 'm_pszData 0x003BBA60 "CSAD|Air Tube (òðóáêà äëÿ îòâîäà òåïëà îò ïðîöåññîðà)|2" wchar_t*'

You see, that russian part is unreadable. My project has Unicode libraries support and I can use Russian in my project, but 'Read string' has the problem. Can you help me?

Re: A Problem with CStdioFile

David Crow25-Dec-06 5:10

David Crow

25-Dec-06 5:10

yaros21 wrote:
...when I use debugger I see that 't' contains is 'm_pszData 0x003BBA60...

Are you viewing it with the "su" debugger symbol?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Re: A Problem with CStdioFile

yaros2125-Dec-06 20:07

yaros21

25-Dec-06 20:07

Thanks you, but I've already solve it. In project properties I switched 'Character set' to 'Use multi-Byte character set' and it works well now. Unicode isn't crucial for my project.

how to Convert FileTimeToSystemTime in win32.

amitmistry_petlad 24-Dec-06 23:06

amitmistry_petlad

24-Dec-06 23:06

i am using the .NET.
i need to fetch the attributes from the wmv/wma file.
e.g. time(created,access,modified)bitrate,size,duration,extension(avi/mpeg/wmv).
i have used the above API function FileTimeToSystemTime(&ft,st)
ft is FILETIME.
where st is LPSYSTEMTIME.
When i debug it gives memory error.
all these attributes i need to display in the listview like search which gives us
all files list information with attributes.

Thanks in advance

amit mistry

Re: how to Convert FileTimeToSystemTime in win32.

includeh1025-Dec-06 2:20

Raise events from unmanaged to managed

25-Dec-06 2:20

LPSYSTEMTIME st
is the same as
SYSTEMTIME*st;

you must do in this way:

SYSTEMTIME st;
FileTimeToSystemTime(&ft,&st)

yoti1124-Dec-06 22:31

yoti11

24-Dec-06 22:31

Hi,

I tried to raise an event from unmanaged code class to a class in managed code.

I passed a delegate pointer (using Marshal) to the unmanaged class but I got an error when the unmanaged class tried to execute the function.
I tried to use pin_ptr to the delegate pointer with no results.

How can I raise event from unmanaged code class to a managed code class using delegate (managed) and function pointer(unmanaged)?

Thanks

Re: Raise events from unmanaged to managed

567890123424-Dec-06 23:15

5678901234

24-Dec-06 23:15

I don't think that it is possible to raise event directly from unmanaged code, but it is possible to call managed callback function which does this. Use Marshal.GetFunctionPointerForDelegate method to pass managed callbak function address to unmanaged code.
Keep delegate instance alive all time when callback function can be called.

Re: Raise events from unmanaged to managed

yoti1124-Dec-06 23:36

yoti11

24-Dec-06 23:36

Thanks for your reply,

I've a delegate instance that lives all the time and I sent it to the unmanaged code using Marshal.GetFunctionPointerForDelegate.

But I think there is a problem with the GC since it can be reallocated the delegate on the heap.

How can it be handle?

Thanks

Re: Raise events from unmanaged to managed

567890123425-Dec-06 1:26

5678901234

25-Dec-06 1:26

I think that that delegate is pinned internally by this function. .NET doesn't allow to take unmanaged pointers to managed unpinned objects.
You can do this manually using GCHandle, as shown in MSDN topic "GCHandle.Alloc Method (Object)", but I think this is exactly what GetFunctionPointerForDelegate does.

uninitialized pointer

rp_suman24-Dec-06 20:58

24-Dec-06 20:58

How to find the pointer is initialized or not.
In destructor, if I delete the pointer array like:
if(ptr)
{
delete [] ptr;
}
an exception is got inside catch(...){}.
The if condition is sucess even if the pointer is not initialized.
The pointer address is 0xcccccccc.
Thanks & Regards,
Suman

includeh1025-Dec-06 2:25

25-Dec-06 2:25

if(ptr)
{
delete [] ptr;
}

is totally bad C++ code.
just do:

delete [] ptr;

because if ptr==NULL, you delete it without any problem.
for code like above, you must init at begining like:

ptr=0;

if the ptr will be reused, you must init after delete like:

delete []ptr;
ptr=0;

Michael Dunn25-Dec-06 5:27

Michael Dunn

25-Dec-06 5:27

Always init your pointers to NULL (0xcccccccc is what the debugger sets uninitialized memory/variables to).
If a pointer's value is NULL, then it's not pointing to anything.
If the value is anything else, it might point to valid memory, or it might not. There is no foolproof way to tell.

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

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Ford, what's this fish doing in my ear?

rp_suman26-Dec-06 19:08

26-Dec-06 19:08

Thanks for help!
In release mode there is no error caught by catch() when deleting unintialized pointer.
I think there is no fixed value for unintialized pointer in release mode.
Is there any chance of deleting the memory of other variable or function when deleting the unintialized pointer?
Is it possible to know the address is some other variable / function's memory.
Thanks & Regards,
Suman

Thanks!! Re: uninitialized pointer

Michael Dunn26-Dec-06 20:57

Michael Dunn

26-Dec-06 20:57

It's your responsibility to make sure any pointer that you dereference is pointing to valid memory. That's why C++ guys make the big bucks Wink | ;)

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

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rp_suman27-Dec-06 15:36

27-Dec-06 15:36

Thank you very much for your great help!
Wishing you a Very Happy and Prosperous New Year 2007!!
Thanks & Regards,
Suman

Cristian Amarie25-Dec-06 5:31

Cristian Amarie

25-Dec-06 5:31

IsBadReadPtr & IsBadWritePtr may help you by indicating if the pointer is readable and/or deletable.
Possibly also HeapWalk could help.

Michael Dunn25-Dec-06 6:31

Michael Dunn

25-Dec-06 6:31

IsBadReadPtr() and IsBadWritePtr() don't work and can actually cause more problems. See this blog[^] for more

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

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Ford, what's this fish doing in my ear?

Cristian Amarie25-Dec-06 7:18

Cristian Amarie

25-Dec-06 7:18

Sorry about that. I didn't know the internal mechanics of these two APIs, nor that their usage can lead to such disasters.
Then I suppose remains HeapWalk... or also this one contains a hidden treasure as well? Smile | :)

rp_suman25-Dec-06 14:02