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Hi everybody,
I have a strange problem with an allocation of memory for pointers of pointers.
i have done this function to allocate memory for 2 pointers of pointers:
void LoadHistoDB::AllocComptStartEndMin(long RowSize,long ColSize)
{
long i;
pComptStartMineure=new double* [RowSize];
pComptEndMineure=new double* [RowSize];
for(i=0;i<rowsize;i++)
{
="" pcomptstartmineure[i]="new" double[colsize];
="" pcomptendmineure[i]="new" }
}
so,="" after="" the="" allocation="" is="" done,="" i="" want="" to="" put="" value="" in="" them,="" ik="" that:
pcomptstartmineure[i][j]="i
pComptEndMineure[i][k]=i
i" don't="" post="" all="" my="" code="" because="" it="" will="" be="" too="" long.
so="" when="" test="" application="" with="" debug="" method="" (calling="" f5!)
when="">120 i could see in the debug window this message in front of pComptStartMineure:
CXX0030:expression cannot be evaluated
and i could see this same message for pComptEndMineure when i>202.
So where is the problem?
Thanks in advance for your help
gérald
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<br />
When i>120 i could see in the debug window this message in front of pComptStartMineure:<br />
<br />
CXX0030:expression cannot be evaluated<br />
<code><br />
<br />
that means that your pointer is pointing to NULL, hence it can not evaluated the value. Normally, an attempt to access NULL pointer will give you "Access Violation" error.<br />
<br />
This dynamic memory allocation is not easy to deal with. Ideally you'll need to go step by step through each line of code and monitor your program and see what is an unexpected result.
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I try to follow first the allocation describe by the function called AllocComptStartEndMin, and you know as usual when you do the allocation of memory for a pointer of "double" for example, p=new double[X]; when you try to see what are the value, for each i from 0 to to X-1 of p[i], (before any affectation), in the debug window, you have in this window:
p[i] in the column "Name" and -6.2774385...e+066 in "Value" column. So when i execute step by step AllocComptStartEndMin, it works even if i>120. So, why when i want to affect value to the pointers i can't affect value for the first pointer when i>120 ( and what is very strange is this value:120, because in my sample RowSize =866 and ColSize=255!)
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Hi,
I'm developing an application where you can configure circuits. the problem is after placing the components on the User Interface I've to make connections. these connections are to be represented by lines.
How do we caluclate the path of a line that does not pass through a certain Area . The lines can be only horizontal or vertical. The line has to pass around a certain specified area.
can anybody help me out with this thanks, in advance
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You're trying to get the circuit to draw itself and therefore not cross ? A basic line intersection algorithm looks like this:
function ccw(p1, p2, p3)
// Slightly deficient function to determine if the two lines p1, p2 and
// p2, p3 turn in counter clockwise direction}
{
var dx1, dx2, dy1, dy2;
dx1 = p2.x - p1.x; dy1 = p2.y - p1.y;
dx2 = p3.x - p2.x; dy2 = p3.y - p2.y;
if (dy1/dx1 < dy2/dx2) return true;
else return false;
}
function intersect(l1, l2)
{
return ((ccw(l1.p1, l1.p2, l2.p1) != ccw(l1.p1, l1.p2, l2.p2))
&& (ccw(l2.p1, l2.p2, l1.p1) != ccw(l2.p1, l2.p2, l1.p2)));
}
That's in JScript, sorry.
Christian
No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002
Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002
During last 10 years, with invention of VB and similar programming environments, every ill-educated moron became able to develop software. - Alex E. - 12-Sept-2002
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Oh I recognize the asteroids guy here...;P
How low can you go ?
(MS rant)
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If you simply want to avoid your lines from crossing, then Christian Graus's solution would work fine. However I think this solution will limit you to very simple layout diagrams.
If you would like your tool to be able to layout complex paths, I would suggest looking up path-finding on Google. I have seen many sample applications, you may be able to find one that will work for you.
Good Luck
Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!
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Sir,
In mainframe the background color is white.I want to change this color to some other color.How can i do that .Please help me in achieving this.
Thanking you,
regards
Subhashree
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In your OnEraseBkgnd draw a window with youur client bound.
Mazy
"If I go crazy then will you still
Call me Superman
If I’m alive and well, will you be
There holding my hand
I’ll keep you by my side with
My superhuman might
Kryptonite"Kryptonite-3 Doors Down
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hello,
how to make an installer or a set up file of a vc++ application.
thanx in advance,
sunil.
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Hello,
now i need some diff help..
I have Visual Studio 6.0 Enterprise Edition.In that there is Pacakge and Deployment Wizard in Microsoft Visual Studio 6.0 tools.
Now problem is that i don't now what all have to be filled in the text boxes that come one after the other.For example I don't no what files have to be included in program files and the configuration files.
So, if anyone can give some site address or an example where there is a a step by step procedure of making an installer of a vc++ application(Using MFC classes), i will be greatful to you.
Once Again Thanx in advance,
sunil.
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If you have the pro or enterprise Installshield recognises the dpendancies for thep roject when you launch it.
This was a great help recently when I used and ActiveX object in a project.
Elaine
Would you like to meet my teddy bear ?
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winamp installer is great
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Hello,
now i need some diff help..
I have Visual Studio 6.0 Enterprise Edition.In that there is Pacakge and Deployment Wizard in Microsoft Visual Studio 6.0 tools.
Now problem is that i don't now what all have to be filled in the text boxes that come one after the other.For example I don't no what files have to be included in program files and the configuration files.
So, if anyone can give some site address or an example where there is a a step by step procedure of making an installer of a vc++ application(Using MFC classes), i will be greatful to you.
Once Again Thanx in advance,
sunil.
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I work with Visual C++ an I've retrived
the number of partitions of the hard-disk
and the number of the volume "C" with the
Windows API functions GetDriveType and
GetVolumeInformation.
Now I'm searching for a function or a
tool (in C/C++) to detect the date when
the "disk C" was formatted, and/or other
peculiarity of hard-disk.
Can somebody give me any suggestion?
- Many thanks
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I have a MFC extension DLL. In my client program, it seems I have to also export the base class of the class that I am using or else because in the header of the class it "includes" the base, when I compile the compiler gives me that it can not find the files for the base class. Is there a way around this? I want the base class to be used ONLY in the DLL. I only want the my inherited class to be exported and no refernce at all to the base class.
Are the resources declared in the DLL only used in the DLL? I heard that the client will first look in the resource files of the EXE then go to the DLLs if it does not locate it there. What does the DLL do? Does it look in the DLL resource files ONLY for what it needs?
Thanks in advance.
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You have to export it all because the fact that your exported class derives from another one affects the object layout: the client must know the details of base classes in order to be able to handle this.
A possible solution is to resort to C++ classic ways to provide data encapsulation: Define the member functions of interest to the client as virtual in an abstract class and do not export your class, but rather a function that returns a pointer to it (through the abstract class interface). I guess this could not be feasible in your case, as MFC is often too rigid to allow this kind of technique to be applied.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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So this means that if I have tons of classes and inherited classes, they will all need to be exported in the DLL.
It seems you would need to rebuild the client everytime the DLL changes (add function to a class). But I know this is one advantage of the DLL is that it doesn't. Under what circumstance would you not need to recompile the client and can continue to use an updated DLL?
Last question. Am I correct to say that the classes in the DLL can only use the resources declared in the DLL?
THanks.
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So this means that if I have tons of classes and inherited classes, they will all need to be exported in the DLL.
Alas, yes. Unless you apply some data hiding technique like the one I described earlier or some sort of the so called pimpl idiom.
It seems you would need to rebuild the client everytime the DLL changes (add function to a class). But I know this is one advantage of the DLL is that it doesn't. Under what circumstance would you not need to recompile the client and can continue to use an updated DLL?
In a strict sense, client recompilation is needed everytime an exported class changes. However, you can (more o less safely) avoid client recompilation when you add static or non-static, non-virtual member functions to a class. As for message handlers, my hunch is that adding new handlers does ot require client recompilation.
Last question. Am I correct to say that the classes in the DLL can only use the resources declared in the DLL?
No. You're entering dangerous territory here, but in general MFC Extension DLLs do need to explicitly state that they're using their own resources with AFX_MANAGE_STATE. This implies that if AFX_MANAGE_STATE is not invoked, resources from the client .EXE will be used instead.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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You can manage the export of the dll functions (classes I dont know) via number (def-file). Then must must not recompile because the interface of the dll is fixed.
Resources is a tricky field. The other response is correct. But you can also load resources directly. You must than use the handles and work with FindResource (MSDN) etc.
Another way coud be that you load the resources somewhere and give the handles (!!!) or copies of them to the dll to work with.
I think if you need resources in the dll, they have to be coded in it.
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I was trying something else and now things seems to get more convoluted. In this one class I want to export, it has many classes that it uses and thus is declared in the header file of the exported classes. From the previous responses, it seems that I have to then exported everything. It almost seems like I have to export every class I have in the DLL.
In one of these classes, I create a non-modal dialog in the one of my classes. Now, I had to export this as well. But then it also came up with that the IDD = IDC_TEST is a undeclared identifier. At this point, I had to take a step back. It seems like it is getting more and more complicated and that the reason to use a DLL is gone.
Anything else I can do?
Thanks.
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Hello, I'm trying tho inherit from a PropertySheet and from a property page...
INTRODUCTION:
I'm trying to be able to resize all the property sheets that need to be resized and in order to avoid all the work for each property sheet and property page, I've decided to inherit from one Property sheet/page that has that function implemented.
PROPERTY SHEET INHERITHANCE FOLOWED STEPS:
In order to inherit from the property sheet I've followed those steps:
1. create the new PopertySheet class.
2. add the member variables, functions and methods.
3. include the header of the class that have all those new methods... into the header file of one of my property sheets.
4. inherit from that new class (see below):
<br />
class CPSEstacio : public CPSAutoRedimensionable
5. change the contructors:
<br />
CPSEstacio::CPSEstacio(UINT nIDCaption, CWnd* pParentWnd, UINT iSelectPage)<br />
:CPSAutoRedimensionable(nIDCaption, pParentWnd, iSelectPage) <br />
RELATED QUESTIONS:
- Why do I need to change the contructors...
- Are these the right steps?
-----------------------------------------------------------------------------
In the property pages I don't understand how to do it:
what happens to the dialog resource that's asked in the creation of the new class?
In VC++6 when you make a new class that's a CPropertyPage, you must tell which dialog resource will it use...
If I don't know which I will use, what do I have to type there?
-----------------------------------------------------------------------------
As always thank you very much...
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Joan Murt wrote:
RELATED QUESTIONS:
- Why do I need to change the contructors...
You want to call the base class constructor at the construction of the page. This way, every class in the hierarchy gets its turn to look at the parameters involved. Only Heaven (and maybe the programmer) knows what information it needs from the parameters, but fact is that CPSAutoRedimensionable in turn will have to call the ctor of CPropertySheet with these parameters.
Joan Murt wrote:
what happens to the dialog resource that's asked in the creation of the new class?
EveryPage has something like
enum { IDD = IDD_PROPPAGE_ASSAY };
in its header file. In the code file IID is handed over to the CPropertyPage ctor, which in turn loads the resource.
Joan Murt wrote:
In VC++6 when you make a new class that's a CPropertyPage, you must tell which dialog resource will it use...
If I don't know which I will use, what do I have to type there?
Normaly, I work the other way round: I create a page with the resource editor and after it looks like my design, I let the code wizard produce a class for it. The resource can be freely modified afterwards, but the connection to the class remains (via the resource name in the enum-statment above).
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Hi Joan,
Steps 4 and 5 are right, but do not suffice: additionally, you've got to replace CPropertySheet with CPSAutoRedimensionable everywhere where CPropertySheet appears, notably in BEGIN_MESSAGE_MAP.
As for why you should change the ctors, it's basic inheritance stuff: a derived class is responsible to call ctors of its base class(es) (except if the default ctor applies); as you've changed the base class, this has to be propagated to the ctors as well.
what happens to the dialog resource that's asked in the creation of the new class?
Property pages are nothing but special dialogs embedded into a property sheet. As dialogs, they must be attached to a dialog resource. If this is not very clear to you, look for some tutorial on property sheets.
Also, I'd like to recommend you Erwin Tratar's Layout Manager for Dialogs, Formviews, DialogBars and PropertyPages
[^], which turns managing resizing into a child's play.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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