Please help - C / C++ / MFC Discussion Boards

S^nyp28-Apr-04 16:14

28-Apr-04 16:14

how do you maximize a child window?? its probably on the oninitialupdate()...help

Actual Linux Penguins were harmed in the creation of this message.

Re: Need help with MDI

Ryan Binns28-Apr-04 17:58

Ryan Binns

28-Apr-04 17:58

Override PreCreateWindow() in your child frame class and make sure cs.style includes WS_MAXIMIZE.

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

Re: Need help with MDI

britonleap26-Jun-04 9:29

britonleap

26-Jun-04 9:29

That doesn't work.
Any other thoughts???
-B

stl's list.. how to delete an item of the list?

kfaday28-Apr-04 14:19

kfaday

28-Apr-04 14:19

stl list & iterators
I've got a list for XML objects. i'm using the std::list

i declare an iteraror, and set it to the beginning of the list

<br />
XML::iterator i = this->begin();<br />

then i want to go to the 'num' positon of the list, so i use this for bucle:

<br />
for(int ii=0; ii<num ;i++, ii++);<br />

that code is ok, i can see what's on the list.
The problem is that i don't know how to delete that position. the following code doesn't seem to work...

<br />
this->erase(i,i);<br />

do you have any ideas? this is my first project with stl.. i've read Eckels Thinking In C++ vol 2 and i can't find anything.. he speaks about a remove method, but i can't use it

thanks!!

Re: stl's list.. how to delete an item of the list?

f6428-Apr-04 14:43

f64

28-Apr-04 14:43

Hi there,
In order to erase only one element, where the iterator is, use this sintax

iterator erase(iterator it);

Let me show you an example

list<int> myList;
list<int>::iterator it;
<br><br>
myList.push_back(1);
myList.push_back(2);
myList.push_back(3);
<br>
for(it = myList.begin(); it!=myList.end(); it++)
    ATLTRACE(_T("%i\n"), *it);    //print the whole list, this is 1, 2 and 3
<br>
it = myList.begin();              //go back to the beginning
it++;                             //move to the second element, 2
<br>
myList.erase(it);                 //erase this element
<br>
//reprint the whole list
for(it = myList.begin(); it!=myList.end(); it++)
    ATLTRACE(_T("%i\n"), *it);    //now it should be 1 and 3

Try it, it should work.

Fabian

Changing source files location

luddet28-Apr-04 14:08

luddet

28-Apr-04 14:08

Hi,

Is there any way to change the location of source files for a project? I have all my sources in one directory and the project files in other directories. Now I would like VS to start looking in that source directory whenever I add a new or existing item.

Is that possible?

regards
Ludde

Re: Changing source files location

luddet29-Apr-04 11:47

luddet

29-Apr-04 11:47

please help.... anyone? I have searched the docs in vain...

Please help

Stefan Troschuetz28-Apr-04 10:10

Stefan Troschuetz

28-Apr-04 10:10

Hi!

Recently i downloaded an article from this page. This project was programmed in C++ with managed extensions and serves as a .NET Wrapper around a existing C++ implementation of random generators and distributions.
I added this project to my solution that consist of a C# windows application. Under VS.NET 2003 everything worked well and i could use the wrapped random generators and distributions.
Unfortunately, i had to move my solution back to VS.NET 2002. My C# windows application still works well, but the downloaded project doesn't get compiled. I receive the following errors, which i noted besides the lines that generate them:

<br />
template<class T><br />
struct ptr_helper<br />
{<br />
typedef T value_type;<br />
typedef T& reference_type;                     //error C2529: 'reference_type' : reference to reference is illegal<br />
typedef const T& rvalue_type;                  //error C2529: 'reference_type' : reference to reference is illegal<br />
static reference_type ref(T& r) { return r; }  //error C2529: 'reference_type' : reference to reference is illegal<br />
static const T& ref(const T& r) { return r; }  //error C2529: 'reference_type' : reference to reference is illegal<br />
};<br />

This struct is declared in a header-file of the existing C++ implementation that gets wrapped by the downloaded project.
Why can i compile this under VS.NET 2003 but not in VS.NET2002? What i can i do?

THX in advance

Re: Please help

Christian Graus28-Apr-04 10:57

Christian Graus

28-Apr-04 10:57

I believe it was VS.NET 2003 that finally fixed a lot of the bugs in Microsofts C++ compiler. If you're passing a reference to a reference, just change the code to not do that. Smile | :)

Christian

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

Using ifstream to read huge binary files

Ron Hinthorn28-Apr-04 9:51

Ron Hinthorn

28-Apr-04 9:51

Does anyone know how to use ifstream to read binary files over 4 GB in size?

Environment: Microsoft Visual C++ 6.0.

We have a simulator that can generate huge amounts of time-series data. We store this data in binary files. We then read that data as needed for charts, map views, etc. To read a particular item, we use the known layout of the binary files to compute the offset from the beginning of the file:

m_iFstream.open(strFName, ios::in | ios::binary);
int totalOffset = timeStepOffset + ObjectOffset + attributeOffset;
char* buf = NULL;
buf = new char[nLength+1];
m_iFstream.seekg(totalOffset, ios::beg);
m_iFstream.read((char*)buf,(sizeof(char)) * nLength);
buf[nLength] = '\0';

We then copy the read buffer into float.

This works great until the offset exceeds the MAX_INT value. To overcome that, I tried a series of relative offsets as needed, using 64-bit integers to provide a little "head room":

m_iFstream.open(strFName, ios::in | ios::binary);
__int64 llTotalOffset = llTimeStepOffset + objectOffset + attributeOffset;
char* buf = NULL;
buf = new char[nLength+1];
int nRemainingOffset;
if (llTotalOffset < INT_MAX)
{
// Single, direct seek is possible.
//m_iFstream.seekg(0);//seek to begining of file
nRemainingOffset = llTotalOffset;
m_iFstream.seekg(nRemainingOffset,ios::beg);//seek from the beginning of the file
}
else
{
// The offset exceeds what an int can represent.
// Must iteratively seek to the location.
int nMaxSeek = INT_MAX;
m_iFstream.seekg(nMaxSeek, ios::beg); // first seek is from the beginning
llTotalOffset -= nMaxSeek;
while(llTotalOffset >= nMaxSeek)
{
m_iFstream.seekg(nMaxSeek, ios::cur);
llTotalOffset -= nMaxSeek;
}
nRemainingOffset = llTotalOffset;
if (nRemainingOffset > 0)
m_iFstream.seekg(nRemainingOffset, ios::cur);
}
m_iFstream.read((char*)buf,(sizeof(char)) * nLength);
buf[nLength] = '\0';

In theory, this should work. In practice, it doesn’t work consistently. I think the failure must be due to the ifstream class not itself being able to store current file offset (ie same issue we had with variable ‘totalOffset’).

Does anyone know how I might be able to use ifstream in this context?

Note that I did look into declaring a specialized char_traits for the stream. I’m no expert with STL file I/O, but it appears to me that the ‘off_type’ and ‘pos_type’ have to correspond to the ‘char_type’ – so I’m hesitant to try this since we are using the file with standard ‘char’ character type.

Thanks in advance for your advice

Ron Hinthorn

Hi,MFC and big data files

Jamie Kenyon28-Apr-04 8:58

Jamie Kenyon

28-Apr-04 8:58

Hi,

I need to load a large text file into my MFC app and later save changes to disk. What is the best way to do this?

Many thanks

Re: Hi,MFC and big data files

David Crow28-Apr-04 9:02

David Crow

28-Apr-04 9:02

How about CFile and its Read() and Write() methods?

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

Re: Hi,MFC and big data files

Jamie Kenyon28-Apr-04 12:21

Jamie Kenyon

28-Apr-04 12:21

Will all of the magical and fantastic container classes MFC seems to have brought, I thought there might be a way to read it into some kind of buffer class or something?

Cheers

Re: Hi,MFC and big data files

l a u r e n28-Apr-04 14:29

l a u r e n

28-Apr-04 14:29

ummmmmmm not really
a file has to be read from the disk and put into memory
whether u do it in lil bits or one big a**ed lump
its all the same
Smile | :)

"there is no spoon"
biz stuff about me

Re: Hi,MFC and big data files

Jamie Kenyon28-Apr-04 23:01

Jamie Kenyon

28-Apr-04 23:01

Cheers

Re: Hi,MFC and big data files

David Crow29-Apr-04 2:40

David Crow

29-Apr-04 2:40

Jamie Kenyon wrote:
I thought there might be a way to read it into some kind of buffer class or something?

The first parameter to CFile::Read() is the buffer.

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

Put the suo and ncb files in another directory

Anonymous28-Apr-04 8:03

Anonymous

28-Apr-04 8:03

Hi.

Is is possible to set up another location for the suo and ncb file? I have a temp-directory in my project directory where all the obj files are put. Before I backup I delete the tmp directory. I want that the suo and ncb files are also put in the temp directory.

Re: Put the suo and ncb files in another directory

Anonymous28-Apr-04 8:18

Anonymous

28-Apr-04 8:18

Or are there tools that only backup the files that are *really* required?

Re: Put the suo and ncb files in another directory

David Crow28-Apr-04 8:55

David Crow

28-Apr-04 8:55

I have a batch file that runs nightly in all of my development folders. It looks like:

del /s /q *.pch
del /s /q *.sbr
del /s /q *.aps
del /s /q *.pdb
del /s /q *.ncb
del /s /q *.opt
del /s /q *.bsc
del /s /q *.ilk
del /s /q *.clw

This keeps the larger files from taking up space on the backup tape unnecessarily.

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

Re: Put the suo and ncb files in another directory

Anonymous28-Apr-04 9:15

Anonymous

28-Apr-04 9:15

Oh yeah. That rules!

Many thanks David Smile | :)

Thread and UpdateData??

bryanbryan28-Apr-04 7:12

bryanbryan

28-Apr-04 7:12

Hi, I'm new in Visual C++, and I have a problem with a thread and the diferents values of the variables.
My thread is constantly (while(1){.....}) working with a variables and y would like to print their values on the main windows, but I can't use UpdateData(FALSE), because me thread is a global rutine and UpdateData is undefined.
So my question is someone could help my amd explin my how can I refresh the main windows with the news values.
I don't know if I have been enough cleared, but I hope you could understand my problem.
Thanks

Re: Thread and UpdateData??

David Crow28-Apr-04 7:25

David Crow

28-Apr-04 7:25

bryanbryan wrote:
My thread is constantly (while(1){.....}) working with a variables and y would like to print their values on the main windows, but I can't use UpdateData(FALSE)...

There's hardly, if ever, a need to use UpdateData(). In your worker thread, simply post a message back to the primary thread (the one that owns the UI) with the values that have been updated.

To get a better understanding of what threads can and cannot do, I suggest:

http://flounder.com/workerthreads.htm
http://flounder.com/uithreads.htm

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

Toolbox and VC++.NET

pmdanger28-Apr-04 7:03

pmdanger

28-Apr-04 7:03

Hi,

I would like to use the Panel component which is on the "Windows Forms" tab in the toolbox of Visual C++.NET

Unfortunately, the icon which representes this component looks like disabled.

How can i do to make it enabled ?

thanks.
Maileen

Passing classes into threads

roadragedave28-Apr-04 6:58

roadragedave

28-Apr-04 6:58

Im creating threads and I want to pass a pointer to the threads, Is is possible to cast a pointer to a class into a DWORD, if so, how is it done???
Here is the code Im working with, its taken straight from the MSDN

void main(void){<br />
<br />
DWORD loadPerThrdID;<br />
HANDLE loadPerThrd;<br />
TCHAR szMsg[80];<br />
<br />
DWORD dwThrdParam; <br />
	<br />
static WmiWrapper Wmi(NULL, NULL, NULL); //Creating object<br />
<br />
loadPerThrd = CreateThread(<br />
	        NULL, 0, <br />
		loadPerThrdFunc,<br />
		&dwThrdParam,<br />
		0, &loadPerThrdID);<br />
		<br />
if(loadPerThrd == NULL){<br />
	wsprintf(szMsg, (TEXT("Create Thread failed for LoadPercentage")));<br />
	MessageBox(NULL, szMsg, NULL, MB_OK);<br />
}<br />
else{<br />
	_getch();<br />
	CloseHandle(loadPerThrd);<br />
}<br />
}<br />
<br />
//Threads function<br />
DWORD WINAPI loadPerThrdFunc (WmiWrapper Wmi)<br />
{<br />
................<br />
}

What can I do to get this to work, or am I completly out??????

Re: Passing classes into threads

David Crow28-Apr-04 7:19

David Crow

28-Apr-04 7:19

roadragedave wrote:
Is is possible to cast a pointer to a class into a DWORD, if so, how is it done???

Both a pointer and a DWORD are 32-bit values.

DWORD WINAPI loadPerThrdFunc( LPVOID param )
{
    DWORD *p = (DWORD *) param;
    TCHAR s[32];
    wsprintf(s, "The thread value is %lu\n", *p)
    MessageBox(s);
}

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

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.