C / C++ / MFC

Creating a linked list; need to know good practices.

22-May-08 7:57

windows works with "windows objects", try to get the desktop window object and.. work with it. I never tried what you want, but i'll start from something like i said.

Recording data is easy, problem is how to get those data.

x87Bliss29-Apr-08 10:38

x87Bliss

29-Apr-08 10:38

I'm creating a linked list that stores two strings in each node.
I quickly drafted the code as:

<br />
struct SongInfo {<br />
    CString Title;<br />
    CString Address;<br />
    SongInfo* next;<br />
};<br />
<br />
void CreateList() { // not an actual function, just to illustrate my allocation<br />
    ...<br />
    if (bINeedAnother) {<br />
        cur->next = new SongInfo;<br />
        cur = cur->next;<br />
    }<br />
    ...<br />
}<br />

I am using CStrings since the length of the strings is unknown. However, since once they are initialized they don't change, I am thinking I should change it to dynamically allocated WCHAR pointers, with the appropriate length for each string. Or is there another practice that would be better?

The other question is on the allocation of the nodes. The number of nodes can be as few as 10, and I've seen as much as 300. Is it a bad idea to allocate one node at a time (i.e. can I rely on Windows to keep the memory unfragmented)? If so, what is a good practice here?

(Sorry for the noobish questions, my programming professor sucked, and her linked lists ALWAYS crashed, and she ALWAYS blamed the OS.)

Re: Creating a linked list; need to know good practices.

Maximilien29-Apr-08 11:16

Maximilien

29-Apr-08 11:16

1. using CString is ok.

2. usually, when building linked lists, we (me) allocate one node at a time;

Best practice in 2008 would be to use STL (list or vector or dequeue).

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Creating a linked list; need to know good practices.

ninjanear21-May-08 3:15

How to change keyboard typematic rate /delay (and led ind.) VC++/MFC? [modified]

21-May-08 3:15

STL containers are well optimized and you have several types where choose. A good practice is using STL (at least, it's my opinion)

Dinamic resizing of vectors was a great help for me some years ago.

ninjanear29-Apr-08 10:05

Re: How to change typematic rate in keyboard?

29-Apr-08 10:05

Hello,

I need to change the typematic rate/delay (moreover accessing leds). is there any way to do it without a device driver?

I have seen some small MFC applications (less than 500kb..) that can access to leds. SDL libray can, Allegro can... but, without using 3rd party libraries only with VC++/MFC?

I need to send data to a custom keyboard (yes, i know it's an output device), but since XP kernel inhibits direct access to hardware i had to find other way to send data without making a device driver and... with typematic and led status i could achieve it (data will be sent so much times as needed, not only once).

All help will be great. Big Grin | :-D

Thanks U.

modified on Wednesday, May 21, 2008 12:31 PM

David Crow29-Apr-08 10:22

Re: How to change typematic rate in keyboard? [modified]

29-Apr-08 10:22

alichan wrote:
I need to change the typematic rate/delay (moreover accessing leds). is there any way to do it without a device driver?

Have you tried changing the following:

HKCU\Control Panel\Keyboard\KeyboardDelay

"Love people and use things, not love things and use people." - Unknown

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

ninjanear20-May-08 23:07

How do I customize the standard property sheet buttons

20-May-08 23:07

I need accessing by low level so much as possible. That i need is more than accessing rate/delay/leds, but maybe i can achieve it using the way you suggest. I don't want to learn to build device drivers for a simple task, only have 1 life Poke tongue | ;-P

... After some mins...
It looks like changes only are applied when you reboot, otherwise it doesn't work and changes aren't applied immediatly. That's not that i need. Frown | :(

I need change the status of leds and typematic rate/delay from code, in run time and still couldn't find a way to do in VC++/MFC ain WXP without using device drivers.
I know it's possible because i saw some comercial software (MFC) that don't install any drivers and change these settings, but how? I dunno. D'Oh! | :doh:

Anyway thx for your help. Wink | ;)

modified on Wednesday, May 21, 2008 9:34 AM

si_6929-Apr-08 7:52

si_69

29-Apr-08 7:52

Hi
How do I customize the standard property sheet buttons

I can change the text of the button using

CWnd *pWnd = GetDlgItem (ID_APPLY_NOW);
pWnd->SetWindowText("Hello");

but what i want to do it add an icon onto the button as well

Can any one help ?

thanks

simon

Re: How do I customize the standard property sheet buttons

David Crow29-Apr-08 8:12

Re: How do I customize the standard property sheet buttons

29-Apr-08 8:12

Associate a CBitmap object with the button and call its SetBitmap() method.

"Love people and use things, not love things and use people." - Unknown

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Hamid_RT29-Apr-08 21:52

Hamid_RT

29-Apr-08 21:52

Does this[^] helpful?

Dynamically Creating Objects

codeinelogic29-Apr-08 6:09

codeinelogic

29-Apr-08 6:09

Im making a class to be used in a final project for my c++ class and in my game i need to create the object "shot" when the user shoots the problem is "this" when declaring Shot=new TImage(this); has to be a part of a member function.... heres my declaration of my class and the snipit of code where i create the object called "shot" please help D'Oh! | :doh:

#ifndef SpaceInvaders<br />
#define SpaceInvaders<br />
//---------------------------------------------------------------------------<br />
#include <Classes.hpp><br />
#include <Controls.hpp><br />
#include <StdCtrls.hpp><br />
#include <Forms.hpp><br />
#include <ExtCtrls.hpp><br />
#include <Graphics.hpp><br />
//---------------------------------------------------------------------------<br />
<br />
class SpaceInvaders{<br />
private:<br />
public:<br />
        TImage *Shot;<br />
        bool __fastcall Collide(TControl *C1, TControl *C2);<br />
        void __fastcall Shots(TControl *C1);<br />
        void UserMovement(TControl *C1);<br />
};<br />
TImage *Shot;

and when i create the object...

<br />
        Shot=new TImage(*TForm1);<br />
        Shot->Parent=Form1;<br />
        //Shot->Picture;<br />
        Shot->Width=15;<br />
        Shot->Proportional=true;<br />
        Shot->Visible=true;<br />
        Shot->Top=ShootFrom_Y;<br />
        Shot->Left=ShootFrom_X-(Shot->Width/2);<br />

Re: Dynamically Creating Objects

David Crow29-Apr-08 7:29

MFC dosen't care about code quality?

29-Apr-08 7:29

What's the problem?

"Love people and use things, not love things and use people." - Unknown

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Naveen29-Apr-08 4:16

Naveen

29-Apr-08 4:16

I have read in a book that, the worst thing you can do for "optimizing the storage of constant data" is declaring a variable like..

CString g_str("this is the worst thing I can do");

Why I said this here because, recently I installed Visual studio 2008 feature pack and today while debuggig, I happened to step into the base class( CWinAppEx ) of my app class. There I found the below code..

CString strRegEntryNameWorkspace = _T("Workspace");
m_strRegSection = strRegEntryNameWorkspace;

With a little surprise, I scrolled the file, and in the top, there was another bunch of such declartions..

static const CString strRegEntryNameControlBars = _T("\\ControlBars");
static const CString strWindowPlacementRegSection = _T("WindowPlacement");
static const CString strRectMainKey = _T("MainWindowRect");
static const CString strFlagsKey = _T("Flags");
static const CString strShowCmdKey = _T("ShowCmd");
static const CString strRegEntryNameSizingBars = _T("\\SizingBars");
static const CString strRegEntryVersion = _T("ControlBarVersion");
static const CString strVersionMajorKey = _T("Major");
static const CString strVersionMinorKey = _T("Minor");

So pathetic Frown | :(

nave

[OpenedFileFinder]

modified on Tuesday, April 29, 2008 10:26 AM

David Crow29-Apr-08 4:32

29-Apr-08 4:32

Naveen wrote:
I have read in a book that, the worst thing you can do for "optimizing the storage of constant data" is declaring a variable like..

CString g_str("this is the worst thing I can do");

Do you, or the book's author, have metrics to back this up?

"Love people and use things, not love things and use people." - Unknown

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Naveen29-Apr-08 4:44

Naveen

29-Apr-08 4:44

It is actually a microsft press release book Smile | :)

. Programming vc++ by David Kruglinski. And the reason is

if you are writing some code like

const char g_pch[] = "test";

the g_pch get stored in the .rdata section of the code. This section hold initialized readonly data. The more stuff you put in the .rdata section, the better because even multpile copy of application is running, no need to create seperate page file.

If you wrote like

const CString g_str("this is the worst thing I can do");

Now you've got the CString object (which is quite small) in the .bss section, and you've also got a character array in the .data section, neither of which can be backed by the EXE file. To make matters worse, when the program starts, the CString class must allocate heap memory for a copy of the characters. You would be much better off using a const character array instead of a CString object.

nave

[OpenedFileFinder]

toxcct29-Apr-08 5:08

toxcct

29-Apr-08 5:08

i guess defining a const CString is somewhat different than defining a CString object.

the optimizer certainly takes the constness in account more easily.

interresting though.

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Naveen29-Apr-08 5:23

Naveen

29-Apr-08 5:23

May be, but not excatly what you get when you declare like

const strRegEntryNameWorkspace[] =_T("Workspace");

and you see some of the variable declared are passed to functions which have LPCTSTR as parameter. Means they are not taking any advantage of the class CString Frown | :(

nave

[OpenedFileFinder]

toxcct29-Apr-08 5:30

toxcct

29-Apr-08 5:30

hum, yes, I answered a bit too fast too... even a const CString, the compiler doesn't really know what the CString class is for, so if you need literals, it's obvious that you have to use const TCHAR*s... or at best, use the resource string table.

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Randor 29-Apr-08 5:51

Randor

29-Apr-08 5:51

CString and optimization should never be used in the same sentence. It is common sense that constant string literals is a more optimized way of storing string literals. There seems to have been a paradigm shift over the years that optimizations are no longer valid. Its funny how Moore's law has accurately predicted the number of transistors and Wirth's law[^] is correctly predicting that applications are increasingly becoming slower and slower.

I have noticed that many software engineers excessively use CStrings and have no concept of passing values through the stack rather than the heap. It is my opinion/philosophy that software engineers should be certified sort of like a doctor or lawyer. We should all be dressed in lab coats and wearing einsteins haircut[^].

Flame away!
-David Delaune

BadKarma29-Apr-08 21:16

BadKarma

29-Apr-08 21:16

Randor wrote:
CString and optimization should never be used in the same sentence. It is common sense that constant string literals is a more optimized way of storing string literals. There seems to have been a paradigm shift over the years that optimizations are no longer valid. Its funny how Moore's law has accurately predicted the number of transistors and Wirth's law[^] is correctly predicting that applications are increasingly becoming slower and slower.

This problem will only grow. Especially with the new .Net languages where you don't need to worry about the memory. I've recently used c# to create a report, due to the enormous data to put into the report the memory it used was about 1 GB. After I closed the report, the memory wasn't freed.
I though no problem, thats why there is a Garbage Collector running.
Yeah right, tried to create the report again and the OutOfMemoryException was thrown.

I rather stick with c/c++ where I can control the memory, in such way I need or see fit.

Randor wrote:
I have noticed that many software engineers excessively use CStrings and have no concept of passing values through the stack rather than the heap. It is my opinion/philosophy that software engineers should be certified sort of like a doctor or lawyer. We should all be dressed in lab coats and wearing einsteins aircut[^].

I like this idea Big Grin | :-D

, We certainly need safety goggles too and a light saber, in case we are attacked by a lowlife BUG Poke tongue | ;-P

codito ergo sum