C / C++ / MFC

Re: Get User Actions While Background Thread Executes

11-Mar-03 9:47

Hi Dave,

Thank-you for your response. I think I'm getting it.

zdisplay() is clearly a worker thread since it is so-started by AfxBeginThread().

I assumed (badly) that since OnUpdateDialog() function (the intensive processing) was started from a message sent BY the zdisplay() function that it too was of the 'worker' variety.

Clearly you are correct, but what tells you that OnUpdateDialog() is considered a 'main' thread rather than a 'worker' thread?

Sorry for all the dumb questions.

Thank-you very much,
Robert
Smile | :)

Dave Bryant11-Mar-03 9:52

Dave Bryant

11-Mar-03 9:52

Windows are associated with the thread in which they are created. When you send or post a message to a window handle, it will be processed by the thread that owns that window (which may be the same thread). In addition, since worker threads do not have a message pump, they cannot process any messages.

Take a look through some of the thread articles, particularly the ones talking about worker threads vs. user interface threads if you are interested.

Dave

Re: Get User Actions While Background Thread Executes

Robert Palma Jr.12-Mar-03 6:15

Re: Get User Actions While Background Thread Executes

12-Mar-03 6:15

Hi Dave,

Thanks again. I wrote a quick little test program to experiment with this and it works just like you indicated - no surprize.

I found PostMessage() in the Win32 SDK and will implement that as well. It looks like it takes the same parameters.

Thanks for helping me through this. I'm an old C warhorse and C++ and MFC are new to me.
Smile | :)

Dave Bryant12-Mar-03 8:12

Dave Bryant

12-Mar-03 8:12

Not a problem

Dave

Re: Get User Actions While Background Thread Executes

TomKat14-Mar-03 16:12

TomKat

14-Mar-03 16:12

who used visual basic knows that it has a holly function :
DoEvents()
it processes events while working !

int i=0;
while(1)
{
i++;
DoEvents();
}

this is the C++ version :
bool DoEvents()
{
MSG msg;
while (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE) == TRUE)
{
if (GetMessage(&msg, NULL, 0, 0) )
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
return TRUE;
}
}
return 0;
}
//rate me or hate me

I am the mighty keeper of the book on knowledge . Contact me to get your copy .

Re: Get User Actions While Background Thread Executes

Robert Palma Jr.15-Mar-03 5:38

confirmation please: a char is 8 bits???

15-Mar-03 5:38

Thanks TomKat! Smile | :)

Kuniva10-Mar-03 10:54

Kuniva

10-Mar-03 10:54

Ok, it may seem like a stupid question, but i feel like i'm going nutts here.
I bought this book on Java, and i was reading some till i came accross this table with data types and their size in bits. Now, assuming (since Java seems to be derived from C) the main data types are the same as in C, a char would be 8 bits right? 1 byte... It's what i always thought though, cause when i open a file in my HEX editor i get one byte per character in the ASCII table.
But what do i see in my (btw reasonably cheap) book??? A char is 16 bits or 2 bytes in size!!!!!!!????? WTF | :WTF:

Am i going nutts (which is most probable), is this a printing error in my book, or does the fact that it says UNICODE behind the char in my book have something to do with it (which i doubt)..?
WHAT IS THE SIZE OF A CHAR IN C IN BYTES OR BITS??? I seek redemption from this insanity erghh i'll quit now lol

Kuniva
--------------------------------------------

valikac10-Mar-03 11:00

valikac

10-Mar-03 11:00

An ASCII character is 8 bits or 1 byte long.

Kuphryn

Kuniva10-Mar-03 11:01

Kuniva

10-Mar-03 11:01

WOOHO THANK U SOOOO MUCH! Rose | [Rose]

Kuniva
--------------------------------------------

Michael Dunn10-Mar-03 11:02

Michael Dunn

10-Mar-03 11:02

A char variable in Java is 2 bytes. A char in variable C/C++ is one byte. This is related to the character encodings the languages use. Unicode characters are 2 bytes each.

--Mike--
THERE IS NO THERE IS NO BUT THERE IS MAGIC PIXIE DUST BUSINESS GENIE CODE PROJECT

Homepage | RightClick-Encrypt | 1ClickPicGrabber

Robert Palma Jr.10-Mar-03 11:36

10-Mar-03 11:36

A CHAR is 8 bits SIGNED.
If you need to handle binary data, use UNSIGNED CHAR.
Smile | :)

Re: std::stack iterator ?

RaajaOfSelf10-Mar-03 17:23

RaajaOfSelf

10-Mar-03 17:23

http://www.codeproject.com/string/CPPStringGuide1.asp -Give s an comprehensive overview of strings ,character

std::stack iterator ?

Maximilien10-Mar-03 10:46

Maximilien

10-Mar-03 10:46

There's no iterator for stack ( as far as MSDN is concerned )

Confused | :confused:

Is there a way to traverse the stack ?

Thanks.
Max.

Maximilien Lincourt
For success one must aquire one's self

valikac10-Mar-03 11:02

valikac

10-Mar-03 11:02

One solution is a while loop and check the status of the stack via empty().

Kuphryn

Re: std::stack iterator ?

Taka Muraoka10-Mar-03 16:10

Taka Muraoka

10-Mar-03 16:10

Maximilien wrote:
There's no iterator for stack

That's right. Because you're only allowed to look at the top element.

If you *must* use a stack (rather than a list or deque) and *must* traverse it, you can always derive from std::stack and then access the underlying data container (yuk Dead | X|

)

You should save yourself and your company years of grief by shooting yourself through the head immediately. Believe me, in the long run it'll turn out better for everyone. - Tyto (at arstechnica)

Awasu 1.0[^]: A free RSS reader with support for Code Project.

How do I modify a BSTR type string?

dazinith10-Mar-03 10:27

dazinith

10-Mar-03 10:27

ok.. i am getting closer and closer to almost having something that almost works..

i have an example of a function that interacts with vb, and it modifies a variable that comes in by making it backwards before returning.. all i am trying to do is be able to set the value of the variable before returning.. the variable is of type BSTR, and i am getting nowhere.. here is an example of modifying the string which works:

void __stdcall FindBankName(LPSTR strFilename, LPSTR strRoutingNumber, BSTR a)
{

	int i, iLen;
		BSTR b;
		LPSTR pA, pB;

		iLen = lstrlen( (LPCSTR) a );

		b = SysAllocStringLen( NULL, iLen );
		
		pA = (LPSTR)a;
		pB = (LPSTR)b + iLen -1;
		
		for ( i = 0; i < iLen; i++ )
			*pB-- = *pA++;
		
		pA = (LPSTR)a;
		pB = (LPSTR)b;
		
		for ( i = 0; i < iLen; i++ )
			*pA++ = *pB++;
		
		SysFreeString( b );

}

here is an example of one of the many many unsuccessful tries which doesn't work:

void __stdcall FindBankName(LPSTR strFilename, LPSTR strRoutingNumber, BSTR a)
{
 	a = SysAllocString ( "Woop Howdi Bob!" );
}

my main purpose here is to be able to set a variable of type BSTR equal to a character array i have..

like:

char szBuffer[60];
// load up szBuffer with whatever
// use k-rad command to set my BSTR variable to the szBuffer

thanks a ton fer everyones help..

still a newb.. cut me some slack :P
-dz

Re: How do I modify a BSTR type string?

Brian Shifrin10-Mar-03 12:53

Brian Shifrin

10-Mar-03 12:53

void __stdcall FindBankName(LPSTR strFilename, LPSTR strRoutingNumber, BSTR a){
a = SysAllocString ( "Woop Howdi Bob!" );
}

First, it's wrong and going to leak memory.

void __stdcall FindBankName(LPSTR strFilename, LPSTR strRoutingNumber, BSTR *a)
{
*a = SysAllocString ( "Woop Howdi Bob!" );
}

Re: How do I modify a BSTR type string?

MAAK10-Mar-03 13:39

MAAK

10-Mar-03 13:39

I am not sure, but according to VC++ source codes, BSTR is actualy an LPWSTR which is by turn a pointer to WCHAR or wide charater type that's used in UNICODE. That means you may use wide charater functions to set its value.

For example, to set the BSTR a paramter that you have in your code we may do this:

int len = wcslen(a); //if lstrlen is workin as ANSI it may return unexpected results

//this is the only way to prevent memory exception without knowing the size of a[]
if(len >= wcslen(L"Testing")) //the 'L' is very important
   wcscpy(a, L"Testing");

This code is to change an existing BSTR variable but if you are making new one then SysAllocString() should be used.

if your string is ANSI then you must convert it first to UNICODE. If you are using VC++7 then the easiest way is to use CStringW, for e.g.:

char buff[] = "Test";
CStringW strw(buff);
wcscpy(a, strw);

Otherwise you should use MultiByteToWideChar() to convert.

List View question

will138310-Mar-03 10:21

will1383

10-Mar-03 10:21

Hi all. I've created a list view with a bunch of columns. My problem is that when the view comes up, the columns aren't expanded so you can see and/or read what they are. Here's how I'm inserting the columns:

pcol.mask = LVCF_TEXT;
pcol.fmt = LVCFMT_CENTER;
pcol.cx = strlen(column_header[index]) * CHAR_PIXEL_WIDTH;
pcol.pszText = column_header[index];
pcol.cchTextMax = COLUMN_WIDTH;
ListView_InsertColumn(hListView,0,&pcol);

And here is how I am inserting into the list view:

// Insert the name into the list
lvItemList.mask = LVIF_TEXT;
lvItemList.iItem = itemIndex;
lvItemList.iSubItem = 0;
lvItemList.pszText = app;
lvItemList.cchTextMax = 128;
// Insert the item into the list
ListView_InsertItem(hListView,&lvItemList);

Nothing fancy going on here just using the normal LV_ITEM and LVITEM structures, and there's no extra funny stuff going into the LPARAM. So my question is what am I doing wrong here? I thought that by specifying the pcol.cx value to the width that I wanted, the width would be automatically setup for me, but that does not seem to be the case.

Any comments are appreciated.
Thanks!

dazinith10-Mar-03 10:35

dazinith

10-Mar-03 10:35

i've never used that method of creating lists.. but ive used bunches of them and have always specified the widths of the columns.. here is how i do mine.. dunno if it'll help er not..

void CTopView::OnInitialUpdate()
{
	CFormView::OnInitialUpdate();

	// set list views to whole row selections
	ListView_SetExtendedListViewStyleEx(m_lstReportList.GetSafeHwnd(), NULL, LVS_EX_FULLROWSELECT | LVS_EX_SUBITEMIMAGES);
	
	m_lstReportList.InsertColumn(0, "Form", LVCFMT_LEFT, 55);
	m_lstReportList.InsertColumn(1, "Description", LVCFMT_LEFT, 238);
	m_lstReportList.InsertColumn(2, "Period", LVCFMT_LEFT, 70);
}

still a newb.. cut me some slack :P
-dz

will138310-Mar-03 10:38

will1383

10-Mar-03 10:38

dazinith wrote:
i've never used that method of creating lists.. but ive used bunches of them and have always specified the widths of the columns.. here is how i do mine.. dunno if it'll help er not..

Yeah, I've used that method in other applications and it works like a charm, but this application is written in Win32, not MFC. Frown | :(

thanks though. Smile | :)

Gotta work with what ya got in this case. Anyone else have a suggestions?

will138310-Mar-03 10:44

will1383

10-Mar-03 10:44

Actually,

Your replay gave me an idea. I checked the MFC code realizing that MFC is just an OO implementation of Win32, and Looked into the InsertColumn. That told me everything I needed to know, which happened to be me forgetting to add the LVCF_WIDTH to the item mask. that took care of my problem.

Thanks!