Re: From txt file to array...c++ .net framework - C / C++ / MFC Discussion Boards

Jun Misugi8-Mar-04 10:22

8-Mar-04 10:22

Hello,

I have the following class structure:

_________________ ________________
| | | |
| ComponentPeer |<-----------| Win32Component|
|________________| |________________|
Î Î
| |
_________________ ________________
| | | |
| ContainerPeer |<-----------| Win32Container|
|________________| |________________|
Î Î
| |
_________________ ________________
| | | |
| Window Peer |<-----------| Win32Window |
|________________| |________________|
Î Î
| |
_________________ ________________
| | | |
| Frame Peer |<-----------| Win32Frame |
|________________| |________________|

All the classes on the left are pure interfaces.
On the right I have abstract classes. The only concrete class is Win32Frame. Win32Component contains a member variable hWnd. Well, if I have a pointer declared as ComponentPeer * which points to a Win32Frame instance I'm unable to get the correct value for hWnd. For example:

ComponentPeer *cp = new Win32Frame();
Win32Frame *ab = dynamic_cast<Win32Frame *>(cp);
HWND hWnd = ab->hWnd;

this code crashes sometimes with an exception (illegal memory access) or my hWnd has not the correct value. Why doesn't it work? Is there any error? And how could I make it work? (I don't want to have a getHwnd method in my multiplatform class componentPeer).
Thanks.

Re: OO Design Problem

Jim Crafton8-Mar-04 10:55

Jim Crafton

8-Mar-04 10:55

Weird, that looks alot like the VCF's class layout.

I don't want to have a getHwnd method in my multiplatform class componentPeer

Well you could do what I did:
VCF::ControlPeer

just have a method called getHandleID (or something like that) and return an unsigned long. Then typecast that to an HWND.

¡El diablo está en mis pantalones! ¡Mire, mire!

Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)!

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Re: OO Design Problem

Navin8-Mar-04 11:00

Navin

8-Mar-04 11:00

Jun Misugi wrote:
Win32Frame *ab = dynamic_cast(cp);
HWND hWnd = ab->hWnd;

Warning! Danger! If you call dynamic_cast, you may get back a NULL if its argument could not be casted to the right class. So always check for NULL in this case.

Remember, even if you win the rat race, you're still a rat.

Re: OO Design Problem

Jun Misugi8-Mar-04 11:07

Jun Misugi

8-Mar-04 11:07

Ok, I have found the problem. I just had to select the option "General-Purpose always" instead of the default "Base-Cast Always *" in Project/Settings/C/C++/C++Language RepresentationMethod.
I don't know what this stuff means but it makes it work correctly. Does anyone know anything about it?

Thank you anyway for answering.

Memory Deallocation problem

gteichner8-Mar-04 9:38

gteichner

8-Mar-04 9:38

I am trying to track down a crash on application exit that causes the program to dump in _free_dbg_lk. This memory deallocation is called from a third party component that I have been using for a while without a problem. I am trying to determine what I changed that is now causing the app to dump on exit.

I know about "no mans land" (0xFD), dynamically allocated but uninitialized memory (0xCD), dynamically allocated and freed memory (0xDD). In this problem the pointer is 0xFEEEFEEE, which I have also seen plenty of times when debugging memory allocation problems.

My question is: Does anybody know what causes a pointer to be changed to 0xFEEEFEEE? This should help me track down what is messing up my application shutdown.

From txt file to array...c++ .net framework

kfresh8-Mar-04 8:57

kfresh

8-Mar-04 8:57

i need some help in getting data from a txt file to an array. i'm using C++ in visual studio .net. and yes i'm a newbie and this is a homework assignment so please be easy on me hahaha...

here's the txt file contents:
75 83 77 91 76
80 90 95 93 48
78 81 11 90 73
92 83 30 69 87
23 45 96 38 59
60 85 45 39 67
27 31 52 74 83
93 94 89 77 97
79 85 28 93 82
85 72 49 75 63

i need to use the numbers in the file for calculations. here's part of my code using StreamReader to get the data from the txt file.

Code:

<br />
int main() <br />
{ <br />
   double average = 0.0; <br />
   int rows = 0; <br />
   int cols = 0; <br />
    <br />
   //declare streamreader <br />
   IO::StreamReader *inData; <br />
   inData = IO::File::OpenText("InData.txt"); <br />
<br />
   //reading records <br />
   while (inData->Peek()) <br />
   { <br />
   } <br />
   inData->Close(); <br />

this is where i get tripped up.. i'm unsure what i need to add to get that data into an array to do calculations. I know i still need to declare the array. i just need to know what do to in the while loop to get the data from the txt file into an array to do calculations. so i guess the data from the files also need to be converted to integers i guess right?

K

Re: From txt file to array...c++ .net framework

Tom Larsen8-Mar-04 9:06

Tom Larsen

8-Mar-04 9:06

Wouldn't sscanf or one of the variants work here? That is you are really using Visual C++. If you are using Managed C++ I believe you can use a ReadLine and then use String.Split to crudely tokenize.

Re: From txt file to array...c++ .net framework

David Crow8-Mar-04 9:16

David Crow

8-Mar-04 9:16

String strLine;
while ((strLine = inData->ReadLine())) != null)
{
    // now parse strLine
}

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: From txt file to array...c++ .net framework

Christian Graus8-Mar-04 10:44

Christian Graus

8-Mar-04 10:44

If you're allowed to use the standard library, an ifstream would actually allow you to read them as ints, no problems at all.

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

Re: From txt file to array...c++ .net framework

kfresh8-Mar-04 10:50

kfresh

8-Mar-04 10:50

nah... have to use it at this .net gayness haha... so i guess is use streamreader??

k

Re: From txt file to array...c++ .net framework

Christian Graus8-Mar-04 10:55

Christian Graus

8-Mar-04 10:55

I suppose so. What idiot is making you use C++.NET ? If you want to use .NET, use C#.

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

Re: From txt file to array...c++ .net framework

kfresh8-Mar-04 10:57

kfresh

8-Mar-04 10:57

it's actually a school assignment... and the gayness of my school... lets do C++ .NET for the first C++ class... but the Object Oriented C++ next semester will be in standard code.... it makes no sense...

k

Re: From txt file to array...c++ .net framework

Christian Graus8-Mar-04 11:05

Christian Graus

8-Mar-04 11:05

They probably think that the .NET framework will make the jump into C++ less painful. I still think C# would have given the same effect with more long term benefit.

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

INI file question

Tom Wright8-Mar-04 8:57

Tom Wright

8-Mar-04 8:57

Do I have to write out the registry key in order to write out an ini file? In my code I'm using the WritePrivateProfileString API passing the section name, key and the path with file name. The file gets created but nothing is written.

In the example in the MSDN lib they show calls made to registry settings. But I just want to write out the file and not making any reg settings.

Here's a snippet of my code:

<br />
	for(int i = 0; i < NumItems; i++)<br />
	{<br />
		if (ListView_GetCheckState(m_cColumnList.GetSafeHwnd(), i))<br />
		{	<br />
			//write out the columns to the ini file<br />
			//AfxMessageBox(m_cColumnList.GetItemText(i, 0));<br />
			WritePrivateProfileString ("Columns", m_cColumnList.GetItemText (i,0), NULL,CurrentDir); <br />
		}<br />
	}<br />

All I want to do is write out the SQL column names to an ini file. So each key will be a column name with no value.

Any help would be appreciated.

Thanks

Tom Wright
tawright915@yahoo.com

Re: INI file question

David Crow8-Mar-04 9:00

David Crow

8-Mar-04 9:00

If the third parameter to WritePrivateProfileString() is NULL, the specified key (the second parameter) will be deleted.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: INI file question

Tom Wright8-Mar-04 9:12

Tom Wright

8-Mar-04 9:12

Is there a way to write out a key without a value?

Thanks

Tom Wright
tawright915@yahoo.com

Re: INI file question

David Crow8-Mar-04 9:20

David Crow

8-Mar-04 9:20

Sure, just ensure that the third parameter is non-NULL.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: INI file question

Tom Wright8-Mar-04 9:22

Tom Wright

8-Mar-04 9:22

Haha....duh. How come you always seem to make me see the light and it's right in front of me?

Thanks again

Tom Wright
tawright915@yahoo.com

Re: INI file question

Tom Wright8-Mar-04 10:16

Tom Wright

8-Mar-04 10:16

Is it possible to put keys in there with out the '=' sign after them. Would I have to open this file like a normal file?

Thanks

Tom Wright
tawright915@yahoo.com

Re: INI file question

David Crow9-Mar-04 1:58

David Crow

9-Mar-04 1:58

Tom Wright wrote:
Is it possible to put keys in there with out the '=' sign after them.

Not and be able to use the ini-related functions.

Tom Wright wrote:
Would I have to open this file like a normal file?

What constitutes normal is how the file is used, not what it contains. You can store the data in a .ini file, but you'd then need to use fscanf(), CFile::Read(), or CStdioFile::ReadString() to operate on it. To avoid future confusion, you might want to make it a .cfg file.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: INI file question

Navin8-Mar-04 10:57

Navin

8-Mar-04 10:57

In all honesty, if I were you, run, don't walk, from WritePrivateProfileString and its ilk. Just open the file like a regular text file. I'm sure there are libraries to handle INI files here on CodeProject, if not, writing your own isn't that big of a deal and will pay off in the long run.

Why don't I like WritePrivateProfileString?
Green Alien | [Alien]

It can fail on 95/98/Me if your file is too big (> 64K)
Green Alien | [Alien]

As you have noticed, it is not very flexible.
Green Alien | [Alien]

I believe the OS may use some funky memory mapping to write the file, so attempts at reading it as a nomral file after calling WritePrivateProfileString may be unpredictable.

Remember, even if you win the rat race, you're still a rat.

Re: INI file question

David Crow9-Mar-04 2:13

David Crow

9-Mar-04 2:13

Navin wrote:
I'm sure there are libraries to handle INI files here on CodeProject, if not, writing your own isn't that big of a deal and will pay off in the long run.

It would be silly to reinvent the wheel. It makes no sense to use something other than WritePrivateProfileString() when writing to a .ini file. If that function does not do what you want, perhaps what you want requires a different tool (I'm thinking of an Abraham Maslow quote here).

Navin wrote:
It can fail on 95/98/Me if your file is too big (> 64K)

If more than 64KB needs to go in such a file, it's time to rethink the design.

Navin wrote:
As you have noticed, it is not very flexible.

Only if you don't know how to use it, or use it for something for which it was not intended.

Navin wrote:
I believe the OS may use some funky memory mapping to write the file, so attempts at reading it as a nomral file after calling WritePrivateProfileString may be unpredictable.

Why use a .ini file if you are not going to use ini-related functions on it?

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Transferring a BMP file on network

prasadddeshpande8-Mar-04 8:09

prasadddeshpande

8-Mar-04 8:09

I am not getting how to transfer a .BMP file from one machine to another using sockets. Plz help me

Re: Transferring a BMP file on network

Atif Mushtaq8-Mar-04 18:56

Atif Mushtaq

8-Mar-04 18:56

Well can u clearly tell what problems u r having , is there some problem regarding socket programming or something else.

Unmanaged in a .NET world

Re: Transferring a BMP file on network

prasadddeshpande10-Mar-04 7:45

prasadddeshpande

10-Mar-04 7:45

In my code On one machine there is a .bmp file
I created one object of CFile & opened that file in binary mode
then one byte pointer is pointing to start of file, for .txt file this pointer holds the pointer to the string, but in my case it is holding header
so i can not send that data on network
If CArchive can be used plz guide me.

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