C / C++ / MFC

Setting a radio button as the default choice

18-Jun-03 4:13

It is usually not very practical (system resources, unwritten files, database connections etc.), and it is extremely annoying during maintenance. I strongly recommend using std::auto_ptr or something similar.

Jay Hova17-Jun-03 9:41

Jay Hova

17-Jun-03 9:41

Hi,

I am extremely new to using MFC, and am programming a simple application with a couple dialog boxes. I created the dialog boxes and the menu items, but I can not figure out how to set one of the radio buttons as the default choice. I was trying to use the CheckRadioButton feature but it doesn't work.

Any help would be appreciated...

Thanks in advance.

valikac17-Jun-03 10:02

valikac

17-Jun-03 10:02

One solution is via resource editor. Look for an option to set the default button. Another solution is to initialize the radio buttons in OnInitDialog(). Call SetCheck().

Kuphryn

David Crow17-Jun-03 10:51

David Crow

17-Jun-03 10:51

If you don't have a member variable for each of the radio buttons, you can use:

BOOL CMyDialog::OnInitDialog()
{
    // assuming there are five radio buttons, set the second one to checked
    CheckRadioButton(ID_RADIO1, ID_RADIO5, ID_RADIO2);
}

Otherwise, create a member variable for each of the radio buttons. Then in OnInitDialog(), set the state of each with SetCheck().

BOOL CMyDialog::OnInitDialog()
{
    // assuming there are five radio buttons, set the second one to checked
    m_btn1.SetCheck(FALSE);
    m_btn2.SetCheck(TRUE);
    m_btn3.SetCheck(FALSE);
    m_btn4.SetCheck(FALSE);
    m_btn5.SetCheck(FALSE);
}

Ryan Binns17-Jun-03 16:18

Ryan Binns

17-Jun-03 16:18

Use ClassWizard to add a member variable tied to the first radio button in the group. The variable will be of type int. In the dialog box class's constructor, you will see that the variable is set to -1. This means that none of the radio buttons are selected. Set this to 0 (for the first radio button in the group), 1 (for the second in the group) etc.

Hope this helps

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

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"

How do you create new object using <vector>?

Jay Hova18-Jun-03 4:16

Jay Hova

18-Jun-03 4:16

Thanks for all the help.

Did the trick.... Smile | :)

kleft17-Jun-03 9:06

kleft

17-Jun-03 9:06

I'm having trouble understanding the use of vectors in C++, perhaps someone could comment about this snippet of code (found on the internet). In particular, the area I'm most confused about is in bold below...

How do you add elements to the list without having to assign objects names first? I'm trying to find a way to nest vectors of stuctures. From posts on this board, I've found that CArray is not recommended.

Here's the snippet of code... It's an array of people, each may have a variable number of nickels (dimes and pennies could be added).

************ nickel.h ********************************
#include < list >
#include < vector >
#include < algorithm >
#include < iostream >
using namespace std;

class nickel
{
public:
nickel();
virtual ~nickel();
};

class person
{
public:
person();
virtual ~person();

void addNickel(nickel *n) {myNickels.push_back(n);}
void removeLastNickel() {myNickels.erase(myNickels.end());}
private:
list < nickel * > myNickels;
};

**********KDlg.cpp*******************
void CKDlg::OnNewPerson()
{
//These don't work
NewNickel = new nickel;
NewPerson = new person; //doesn't work
NewPerson.addNickel(NewNickle) //expected constant expression

//This works, but forces me to assign objects to each element of the array...seems to defeat the purpose of a resizable array.
person p1,p2;
nickel n1,n2,n3;
p1.addNickel(&n1);
}

Re: How do you create new object using ?

AlexO17-Jun-03 9:14

using SP_DRVINFO_DATA_V2 instead of SP_DRVINFO_DATA_V1

17-Jun-03 9:14

nickel* nn = new nickel;
person* np = new person;
np->addNickel(nn);

tessierjf17-Jun-03 8:28

tessierjf

17-Jun-03 8:28

Hi!

I'm developing on a Win2k platform and I need to use the SP_DRVINFO_DATA to be defined as SP_DRVINFO_DATA_V2 instead of SP_DRVINFO_DATA_V1. As stated in MSDN:

"If your component will be used only on Windows 2000 and later, do not define the identifier. If the identifier is not defined, SP_DRVINFO_DATA_V2 is used."

Here's the define they're talking about: #define USE_SP_DRVINFO_DATA_V1 1

Obviously, I didn't defined this but SP_DRVINFO_DATA is still defined as SP_DRVINFO_DATA_V1.

Then, I went to the setupAPI.h file to see what was going on:

#if USE_SP_DRVINFO_DATA_V1 || (_SETUPAPI_VER < 0x0500)
...
typedef SP_DRVINFO_DATA_V1 SP_DRVINFO_DATA;
#else
***
typedef SP_DRVINFO_DATA_V2 SP_DRVINFO_DATA;

Since I didn't define the first condition, it's obvisous that the _SETUPAPI_VER is < than 0x0500. _SETUPAPI_VER is actually defined as (in my environment)

#if defined(_WIN32_WINNT) && (!defined(_WIN32_WINDOWS) || (_WIN32_WINNT < _WIN32_WINDOWS))
#define _SETUPAPI_VER _WIN32_WINNT // SetupAPI version follows Windows NT version

_WIN32_WINNT as a value of 0x0400. If I change this value (to 0x0500 for instance)or if I don't define it at all, some other stuff break in my code (error LNK2001: unresolved external symbol _CLSID_DOMDocument40)

Anyone has an idea how I could fix this conflict? Thanks in advance!

Jean-Francois !

storing data in Memory and accessing it for playback

johnstonsk17-Jun-03 7:58

johnstonsk

17-Jun-03 7:58

I got a rather difficult question for the group.

Here it is:
I have created a program that records flight simulator data. I added a feature that allows the user to record the data to a file.

I would like to have a feature that wrote the simulator data to memory and if the user wanted to playback the data they would hit a button and the data that was written to memory would be played back.

I was thinking alongs the lines as a circulatory buffer. (Once it reaches the end it starts over) I thought about making a timestamp, so they can choose from time (a) to time (b)

I don't know how large to make the buffer?

This program is the only thing running on the machine besides Windows

Any ideas on how I should go about this?

thanks,
steven

Re: storing data in Memory and accessing it for playback

AlexO17-Jun-03 8:39

Re: storing data in Memory and accessing it for playback

17-Jun-03 8:39

You might want to consider Memory file. It is resizable and it automatically maps physical file into memory.

AlexO17-Jun-03 8:47

Re: storing data in Memory and accessing it for playback

17-Jun-03 8:47

MSDN "Managing Memory-Mapped Files in Win32"

johnstonsk17-Jun-03 8:47

johnstonsk

17-Jun-03 8:47

is this a type of file or a class?

What exactly is a memory file?

steven

ActiveX control stock property issue.

Marion2817-Jun-03 7:30

Marion28

17-Jun-03 7:30

Hi all,
I'm writing an ActiveX button control that uses the Caption stock property to display the text on the face of the button. I'm having a big problem getting the caption stock property to work correctly. I've added the caption stock property to my control class using the automation tab of classwizard, and added the appropriate drawing code in my OnDraw() function of the control. Everything works fine using the activex test container, but everything goes haywire in the program I embed the control in. In the application, the button face displays the caption as entered into the property page of the control, but when I try to change the caption using the stock caption put property method, the first time it will change, then any subsequent changes are not reflected, and the text on the button face is frozen (cannot be changed). This is also reflected in the VC++ 6.0 IDE. When I open the control property page in the IDE of the project I'm embedding the control in, and set the caption for the first time, it looks fine. But when if I need to change the caption in the IDE using the property page, it reverts back to the original caption. Does anyone have any ideas?

The activex control project runs under windows 2000, and compiles and registers fine. The project I'm embeding the control under also runs under windows 2000 and has no compile errors, but also uses the directx sdk.

I'm willing to send the source code for both projects to anyone willing to help me with this issue.

Please help!! This problem is maddening to me.

Thanks all,
Marion Cry | :((

Function to pass an CArray or Structure..

RobJones17-Jun-03 6:58

RobJones

17-Jun-03 6:58

This maybe an easy question.. How do I write a function that can return a pointer to a CArray or a structure?

Whoever said nothing's impossible never tried slamming a revolving door!

Re: Function to pass an CArray or Structure..

basementman17-Jun-03 7:05

basementman

17-Jun-03 7:05

Either pass in a pointer to a CArray and fill it in the function, or allocate a new CArray from the heap and return a pointer to it (don't forget to delete it!). EX:

METHOD 1:
void SomeFunc()
{
CArray oArray;

ArrayFunc(&oArray);
}

void ArrayFunc(CArray *pArray)
{
pArray->Add(?);
pArray->Add(??);
}

METHOD 2:
void SomeFunc()
{
CArray *pArray = ArrayFunc();
if (pArray)
{
// do something with it...

delete pArray;
}
}

CArray *ArrayFunc()
{
CArray *pRetval = new CArray;

if (pRetval)
{
pRetval->Add(?);
pRetval->Add(??);
}

return pRetval;
}

<span style="border: 2px outset silver;background-color:yellow;color:green;font-family:Verdana,Arial;font-size:8pt;font-style:italic"> onwards and upwards... </span>

Re: Function to pass an CArray or Structure..

RobJones17-Jun-03 7:12

RobJones

17-Jun-03 7:12

Thanks for the quick reply!! I knew I was doing something stupid Big Grin | :-D

Rob

Whoever said nothing's impossible never tried slamming a revolving door!

Re: Function to pass an CArray or Structure..

peterchen17-Jun-03 7:12

peterchen

17-Jun-03 7:12

basically, it's easy:

CArray * GetMyArray()
{
  // you could allocate a new array here like this:
  CArray * newArray = new CArray;
  newArray->SetSize(yadda);
  ... 
  return newArray;
  // or return a pointertr to a "permanent" array
}

However, to allocate memory inside the class, and requiring the caller to free it, is often a bad idea. If possible wrap he resource in a class, or use a smart pointer to a reference-counted class.

"Der Geist des Kriegers ist erwacht / Ich hab die Macht" StS

sighist | Agile Programming | doxygen

non-blocking mode in sockets

User 988517-Jun-03 6:33

User 9885

17-Jun-03 6:33

I have an IOCP based server. Currently the sockets are in blocking mode, but I want to change them to non-blocking. Is there any known ill-effects of using overlapped reads and writes, IOCP, and non-blocking sockets?

Note: I googled and went through MSDN, and could not find anything that discusses this combination. Now, I need experienced people to guide me Smile | :)

Thank you.

Thomas

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

David Crow17-Jun-03 6:51

David Crow

17-Jun-03 6:51

Thomas George wrote:
Is there any known ill-effects of using overlapped reads and writes...

As long as they are not to/from the same memory address.

User 988517-Jun-03 7:04

User 9885

17-Jun-03 7:04

I meant, when used with a non-blocking socket. I use overlapped reads and writes with blocking sockets, and they are fine. I want to convert the socket to a non-blocking one.

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

valikac17-Jun-03 7:46

valikac

17-Jun-03 7:46

IOCP is non-blocking I/O. What do you mean overlapped read and write? Under IOCP I/O model, one or more threads processes I/O requires and update the main process.

Kuphryn

User 988517-Jun-03 7:59

User 9885

17-Jun-03 7:59

There has to be a pending read on the socket for IOCP to get notified. So I have an asynchronous read pending on the sockets that are added to the IOCP. Now, I do this with blocking mode sockets, and when a thread wakes up because of an activity on the socket, I used to do recv to get some more data. I don't want the recv call to block, but just return, if there is no more data. So, I want to convert the socket to non-blocking. Since I have never used it, I was wondering whether anyone had any experience with it.

Thomas

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.