C / C++ / MFC

memset equivilent for std::vector

18-Jul-02 9:48

To the best of my knowledge, all windows have the same caption height (or no caption at all). Windows with nonstandard captions are faking the effect by omitting the system-provided caption and painting something similar on the client area.
If I'm wrong, please someone correct me.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

moredip18-Jul-02 7:38

18-Jul-02 7:38

Howdy everyone,

Quick STL question for y'all...

I'm having lots of fun Poke tongue | ;-P

converting some old code from C arrays to std::vectors.

I've got a bool *m_abMatched, and at the start of a function the array must be initialised to false. At the moment this is done with memset( m_abMatched, false, m_cbMatched*sizeof(bool) ).

If I replaced the array with a std::vector<bool> how would I set all the elements of the vector to false? Is m_abMatched::assign( m_abMatched.size(), false ) the correct approach?

TIA,

Pete

Joaquín M López Muñoz18-Jul-02 7:54

18-Jul-02 7:54

Yes, this is correct.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

moredip18-Jul-02 7:56

18-Jul-02 7:56

Joaquin to the rescue again Big Grin | :-D

Thanks!

C^hris L^osinger18-Jul-02 8:09

18-Jul-02 8:09

it may be correct. but it is an absolutely horrible thing to do, IMO.

To explain Donald Knuth's relevance to computing is like explaining Paul's relevance to the Catholic Church. He isn't God, he isn't the Son of God, but he was sent by God to explain God to the masses.
/. #3848917

moredip18-Jul-02 8:12

18-Jul-02 8:12

how so? What would be a better technique???

C^hris L^osinger18-Jul-02 8:21

18-Jul-02 8:21

it's true that std::vector is actually spec'd in such a way that running memset on it is perfectly legal, i don't argue that. and, i'm sure it was spec'd that way to specifically allow it to be used as a solid chunk of memory.

but to me, using memset is an abuse of the idea of a vector as an abstract container class. plus, there is an accepable STL/OOP friendly way to do what you're describing:

this will create a vector of 20 bool's all set to false.

std::vector<bool> m(20, false);

-c

moredip18-Jul-02 8:24

18-Jul-02 8:24

I wasn't asking about using memset, I was asking what to use to _replace_ memset on a C array.

I'm assuming using m_abMatched.assign( m_abMatched.size(), false ) would be a little bit quicker (and clearer) than m_abMatched = std::vector<bool>( m_abMatched.size(), false), right?

Thanks,

Pete

C^hris L^osinger18-Jul-02 8:29

18-Jul-02 8:29

yeah, that was my evil twin, trying to toss some confusion into other people's lives.

i'll send him away

-c

moredip18-Jul-02 8:33

18-Jul-02 8:33

Damn those evil twins. Mine causes no end of trouble Roll eyes | :rolleyes:

Anyways, std::fill() is more understandable than std::vector::assign() in this case

Pete

Joaquín M López Muñoz18-Jul-02 8:22

18-Jul-02 8:22

This is a more understandable form:

std::fill(v.begin(),v.end(),false);

Nevertheless, the latter is less advisable in some pedantic subtle way, namely that std::vector::assign could be partially specialized to perform faster on some primitive types (not that VC++ does it, anyway.)

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

C^hris L^osinger18-Jul-02 8:24

18-Jul-02 8:24

more understandable, and safer...

it's pretty easy to see memset flying off the end of the vector and writing into the stack somewhere. Smile | :)

-c

Joaquín M López Muñoz18-Jul-02 8:28

creating a new document template

18-Jul-02 8:28

?? Maybe you have misread the guy's question. He was asking about the suitability of

m_abMatched::assign(m_abMatched.size(), false)

as a replacement of memset. And this (assign) is perfectly safe.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

NickWhoForgotHisPasswordToLogIn18-Jul-02 6:45

NickWhoForgotHisPasswordToLogIn

18-Jul-02 6:45

Hello,

I have a few questions I'd like to ask and see if anybody knows anything about this.

First of all, my MDI project starts with an open window. This is great. I want this window to be uncloseable. How do I disable the X (close) button? I want this window never to close.

Second, I get live images in one window, but I'd like to snap and have the image appear in a new window. Right now, the snap appears in the same type of window, so the same type of options apply to it (chaning the contrast or brightness or any example you can think of). I want the snap window to have a different set of avaible drop down options (i.e. I'd like to make some grayed out or unusable).
So I am thinking using a new document template would be the way to go here.

What do you guys think about that? And if you could answer how to gray out the options and how to make sure my first window never closes, I'd sure like to know how to do that. Pleas let me know if I am on the right track with using a new Document Template.

Thanks guys,

NickOne
You guys rock!

p.s. How can I tell if there is a memory leak? Sometimes my program, when I try to close the window crashes and becomes unresponsive. This is a feature I sure don't like!!! Any ideas?

Thanks again!!

Re: creating a new document template

Jon Sagara18-Jul-02 8:00

Jon Sagara

18-Jul-02 8:00

NickWhoForgotHisPasswordToLogIn wrote:
NickWhoForgotHisPasswordToLogIn

Lookup your password here

Jon Sagara

"Me fail English? That's unpossible."
"Hello Supernintendo Chalmers. I'm lernding."
--- Ralph Wiggum ---

Re: creating a new document template

Joaquín M López Muñoz18-Jul-02 8:10

18-Jul-02 8:10

In response to your p.s., memory leaks do not usually manifest the way you describe. In debug mode, MFC apps come with a built-in leak detector: upon exiting, the leaks detected are reported to the debug output window of Visual Studio.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

CreateWindow

confalonieri18-Jul-02 6:35

confalonieri

18-Jul-02 6:35

Hi,

In my application I need to create an empty window just to receive messages and treat them. I wrote the following code:

HINSTANCE hApi = (HINSTANCE) GetModuleHandle(NULL);

if (! hApi) ...// manage error

CHAR * WindowClassName = "MyWindowClass";

WNDCLASS WindowClassInfo;

if (! GetClassInfo(hApi, WindowClassName, &WindowClassInfo))
{
WindowClassInfo.hCursor = NULL;
WindowClassInfo.hIcon = NULL;
WindowClassInfo.lpszMenuName = NULL;
WindowClassInfo.lpszClassName = WindowClassName;
WindowClassInfo.hbrBackground = NULL;
WindowClassInfo.hInstance = hApi;
WindowClassInfo.style = CS_OWNDC | CS_VREDRAW | S_HREDRAW;
WindowClassInfo.lpfnWndProc = (WNDPROC) MyProc;
WindowClassInfo.cbClsExtra = 0;
WindowClassInfo.cbWndExtra = 0;

if (! RegisterClass(&WindowClassInfo)) ...//manage error
}

HWND hWnd = CreateWindow(WindowClassName,
"MyWindow",
WS_OVERLAPPEDWINDOW,
0,
0,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hApi,
NULL);

if (! hWnd) ...//manage error

But, unfortunately, CreateWindow return NULL and GetLastError return 0 !!!

Did anybody could help me ?

Thanks in advance.

Robin.

Joaquín M López Muñoz18-Jul-02 7:34

18-Jul-02 7:34

Everything seems OK. The only possible problem I can think of is that MyProc is not properly declared as a WINDPROC should. Could you show us this function?

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

confalonieri18-Jul-02 22:33

confalonieri

18-Jul-02 22:33

MyProc is declared in a header as following:

LRESULT CALLBACK fidLinkEventProc(HWND _hWnd, UINT _iMsg, WPARAM _wParam, LPARAM _lParam);

and MyProc is defined in a .c file:

LRESULT CALLBACK MyProc(HWND _hWnd, UINT _iMsg, WPARAM _wParam, LPARAM _lParam)
{
switch (_iMsg)
{
...
}

return 0;
}

Ernest Laurentin18-Jul-02 10:01

Ernest Laurentin

18-Jul-02 10:01

Try this, if it work, check your WindowProc function like Joaquim suggested:

LPCTSTR szWindowClassName = _T("MyWindowClass");

WNDCLASS WindowClassInfo;

if (!GetClassInfo(hApi,szWindowClassName, &WindowClassInfo))
{
    WindowClassInfo.hCursor = NULL;
    WindowClassInfo.hIcon = NULL;
    WindowClassInfo.lpszMenuName = NULL;
    WindowClassInfo.lpszClassName = szWindowClassName;
    WindowClassInfo.hbrBackground = NULL;
    WindowClassInfo.hInstance = hApi;
    WindowClassInfo.style = CS_OWNDC | CS_VREDRAW | CS_HREDRAW;
    WindowClassInfo.lpfnWndProc = (WNDPROC) ::DefWindowProc;
    WindowClassInfo.cbClsExtra = 0;
    WindowClassInfo.cbWndExtra = 0;

    if (!RegisterClass(&WindowClassInfo))
    {
        TRACE( " ERROR \n");
    }
}

HWND hWnd = CreateWindow(szWindowClassName,
            "MyWindow",
            WS_OVERLAPPEDWINDOW,
            0,
            0,
            CW_USEDEFAULT,
            CW_USEDEFAULT,
            NULL,
            NULL,
            hApi,
            NULL);
ASSERT( hWnd != NULL );

confalonieri18-Jul-02 23:45

confalonieri

18-Jul-02 23:45

Thank for your help. I solved my problem: MyProc was always returning 0 whatever the message was, whereas it has to treat Windows messages such as "WM_CREATE", ... (traditional messages to create a window).

Now, I use "return DefWindowProc(_hWnd,_iMsg,_wParam,_lParam)" when I receive a Windows message different from my messages.

MultiColumn Listbox

RuiSantiago18-Jul-02 6:17

RuiSantiago

18-Jul-02 6:17

Hi! I'm new at Visual C++, and i was trying to use a CListBox with multicolumn features, but i cannot find a way to include the column's labels.

I guess this must be a easy task for most of you, but i'm really having dificulties in implementing this.

Can anyone help me? Please...

Thank you in advance

Re: MultiColumn Listbox

Joaquín M López Muñoz18-Jul-02 7:49