|
Hi,
I have the following code that won't compile with the error:
e:\PROGRAMMING\SANDBOX\RTTI\dynamic_cast1.cpp(31): error C2683: dynamic_cast : 'A' is not a polymorphic type
<br />
#include "stdafx.h"<br />
<br />
using namespace std;<br />
<br />
class A { };<br />
<br />
class B { };<br />
<br />
void f()<br />
{<br />
A* pa = new A;<br />
B* pb = new B;<br />
void* pv = dynamic_cast<void*>(pa);<br />
pv = dynamic_cast<void*>(pb);<br />
}<br />
<br />
int main()<br />
{<br />
return 0;<br />
}
It's an example in VStudio and is expected to work. Can anyone help me make sense of the error message? TIA!
I am a SysAdmin, I battle my own daemons.
|
|
|
|
|
sorry I just found out the solution, to use dynamic_cast on an expression the underlying object must have at least 1 virtual function.
-- modified at 7:49 Saturday 11th August, 2007
however the following is supposed to cause a runtime exception but doesn't:
<br />
class E<br />
{<br />
public:<br />
void func()<br />
{<br />
cout << "func from E" << endl;<br />
}<br />
};<br />
<br />
class F<br />
{<br />
public:<br />
void func()<br />
{<br />
cout << "func from F" << endl;<br />
}<br />
};<br />
<br />
<br />
void f()<br />
{<br />
E* pe = new E;<br />
F* pf = dynamic_cast<F*>(pe);
}
as well as the following (works but shouldn't because pB is just an instance of B)
<br />
#include "stdafx.h"<br />
<br />
using namespace std;<br />
<br />
<br />
class B <br />
{<br />
public:<br />
int BMem;<br />
void funcB()<br />
{<br />
BMem = 2;<br />
cout << "funcB: " << BMem << endl;<br />
}<br />
};<br />
<br />
class D : public B <br />
{ <br />
public:<br />
int DMem;<br />
void funcD()<br />
{<br />
DMem = 4;<br />
cout << "funcD: " << DMem << endl;<br />
}<br />
<br />
};<br />
<br />
void f(B* pb, D* pd)<br />
{<br />
D* pd2 = static_cast<D*>(pb);
pd2->funcD();<br />
<br />
B* pb2 = static_cast<B*>(pd);
pb2->funcB();<br />
}<br />
<br />
int main()<br />
{<br />
cout << "Main - Start" << endl;<br />
<br />
B* pB = new B;<br />
D* pD = new D;<br />
<br />
f(pB, pD);<br />
<br />
cout << "Main - End" << endl;<br />
}<br />
its output is:
<br />
Main - Start<br />
funcD: 4<br />
funcB: 2<br />
Main - End<br />
-- modified at 8:36 Saturday 11th August, 2007
I am a SysAdmin, I battle my own daemons.
|
|
|
|
|
Hi, I am using visual Studio 2005 C++/CLI. What is available to help me format my output to the printer. I keep finding read only properties. I can use PageScale() to get the display output to fit on the printed page but the printed output is "scrunched up". I have tried playing with PrinterSettings::CreateMeasurmentGraphics() with no success. Is using this function the right approach?
Thanks,
Buck
Buck
|
|
|
|
|
Hi, I'm using visual Studio C++/CLI. I found an example in Visual Basic and followed these steps. Using the Toolbox in the form designer I added printDialog1 and printDocument1 to my Form1. Then I modified printDialog1 and set the AllowSelection and AllowSomePages properties to true and the Document property to printDocument1. This association would seem to imply that printDocument1 would contain the contents of Form1 but evidently it doesn't. I set up the fileToolStripMenuItem to have a printToolStripMenuItem and then double clicked on it to get the function header and modified it as follows...
private: System::Void printToolStripMenuItem_Click(System::Object^ sender, System::EventArgs^ e)
{
if(printDialog1->ShowDialog() == System::Windows::Forms::DialogResult::OK)
printDocument1->Print();
}
This prints a blank page. How do I associate the graphics on my screen with printDocument1 so it will actually come out of the printer? I know this is probably incredibly trivial but most people don't document the trivial. For example, in order to be able to paint I needed to know the screen size. After googling "C++ .NET display size" I got no help. Then I tried "C++ .NET screen size" and still didn't find anything. After an hour or so I stumbled onto Screen::Bounds. I didn't even know the Screen class existed! I have five texts on C++ 2005 and none of them list the Screen class in the index (or a lot of other classes that I have found by accident that seem to be important or useful). So I would not be surprised if there is a command that takes the information from the screen and copies it to printDocument1, but is so basic that everyone knows how to do it already, everyone except the people that have never done it before. What's the $64,000 answer here?
Thanks
Buck
|
|
|
|
|
Hi Buck,
I will find you where ever you go...
For 64K$ I would say:
it all depends on the correlation between a document on screen and a document on paper.
Some programs keep them identical (e.g. MS Word can show what it will print almost
exactly). Other apps don't care, they show one thing, and print an equivalent but
completely different thing.
I have a simple case in my Sokoban article; it displays a board game (that fits on
a screen, no scrolling involved), and can print it on one page.
The essence is you reuse the code that currently sits in your OnPaint handler (it
will require a minor reorganization, splitting the top few lines from the body).
If your wafer would fit on one page, even when it needs some scrolling on screen,
I strongly suggest you have a look at my article's code.
Greetings
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
I read the article and looked at the source code. It wasn't any help. There is no handler named OnPaint. Bottom line is all I can print are blank pages.
Buck
|
|
|
|
|
Hi Buck,
in LP_Sokoban's file Board.cs there is a line
Paint+=new PaintEventHandler(Board_Paint);
which is an alternative way to install a paint handler; in this case it is called
Board_Paint, and it expects to get two arguments, rather than one, but apart from
that it is identical to an OnPaint() method, which is the normal way of installing
a paint handler in a derived class.
And as you can see it immediately calls another method
public void Painter(Graphics g, int panelWidth, int panelHeight, int<br />
fillPercentage, bool printing) passing not the eventargs thing, but the
actual values it needs.
Same Painter method also gets called by PrintableBoard_PrintPage() which is the
PrintPage handler for my public class PrintableBoard : PrintDocument;
this handler too get installed explicitly, hence its name differs from OnPrintPage.
Hope this helps.
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
Hi Luc,
Thanks for the info. While you were responding I was digging into another article that showed an additional function that I did not have called printDocument1_PrintPage(). Seeing that this function had the same general naming convention as other Form1 design controls, I went back to the Form1 design page and double-clicked on printDocument1 and the following code was added...
private: System::Void printDocument1_PrintPage(System::Object^ sender, System::Drawing::Printing::PrintPageEventArgs^ e)
{
DisplayWaferMap(e->Graphics); // I added this line and began receiving printed output
}
Granted, the size of the printed page has to be scaled correctly but at least now I am getting printed output.
Thanks again,
Buck
|
|
|
|
|
Seems like your e-mail notification problem got fixed ?
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
hi i am having a 3d mesh .x file. how to load this using directx managed code. i am new to directx please help me.
|
|
|
|
|
need help regarding a project. me n a friend of mine r thinking to make a voice for converting voice into text as our final year project can i get help regarding it, like what all r we supposed to do. plz do help me need it quick
Never follow anyone but learn from everyone
|
|
|
|
|
good luck with that, I'm sure you won't fail to impress
|
|
|
|
|
I don't want to crush your creativity or anything but Voice Recognition software is very hard to make. I think if you had the knowledge and skills to pull it off you wouldn't be asking here.
Thats not ment as an insult, I cirtainly couldn't pull off making that sort of software in a short time frame and probably could never pull it off by myself, just as a reality check.
You'd be much better off picking something small and simple that you can complete and do well. A large unfinished and badly coded project will get you much worse marks.
|
|
|
|
|
|
As far as I could see they wanted to write a voice to text app rather than use a voice to text component.
|
|
|
|
|
Reet Dhiman wrote: plz do help me need it quick
When I was doing my final year project, I actually had to do it myself why not try that!
You won't learn if someone does it for you, if you just want to learn how to do this (rather than us coding it) then I suggest google as your friend.
Don't want to be mean but a final year project is a test of you skill/knowledge, if someone else does it for you then you don't deserve to pass.
regards,
|
|
|
|
|
Hi, I am using Visual Studio 2005 C++/CLI. I am trying to pass an array from one object to another through a function. I get the above error which I find confusing because they seem to match. Why can't it convert? Or maybe you can show me the best way to copy an array of structures from Object A to Object B (because A will go away before B).
// Defined in Wafer.h -------------------------------------
value struct Die
{
int nXcoord;
int nYcoord;
int nBin;
};
array<Die>^ Failed;
void TransferFailedArray(array<Die>^ failed_die);
// Defined in FailMap.h -------------------------------------
value struct Die
{
int nXcoord;
int nYcoord;
int nBin;
};
array<Die>^ FailedDie;
// Defined in Form1.h ---------------------------------------
// Wafer^ is instantiated in Form1 constructor.
CFailMap^ FailMap = gcnew CFailMap();
Wafer->DeviceName = FailMap->DeviceName;
Wafer->LotNumber = FailMap->LotName;
Wafer->WaferNumber = FailMap->WaferName;
Wafer->TransferFailedArray(FailMap->FailedDie); // This line gives the error
// Defined in Wafer.cpp -------------------------------------
void CWafer::TransferFailedArray(array<Die>^ failed_die)
{
failed_die->Copy(failed_die, this->Failed, failed_die->Length);
failed_die->CopyTo(Failed, 0);
}
Does anyone see a problem with the syntax in here for defining the function?
Thanks
Buck
|
|
|
|
|
Hi Buck,
I think you are looking at the wrong line.
BTW: I suggest you make Visual display line numbers (see my sig), then look at the
details of the compiler's error messages.
failed_die->Copy is not OK, Copy is a static method in the Array class;
as opposed to CopyTo which is an instance method.
Furthermore:
do you really need to copy the array ? an array is an object, so you can store
its reference as often as you want; it will get garbage collected only after all
references to it become unreachable.
So the only way I see to copy an array would be if you need two arrays that initially
contain the same data, but then go live their separate lives, and may be modified
independently from one another.
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
Thanks, I have been thinking of the gc from a scope point of view, that when the function returned the gc would do it's thing and my FailMap reference would be lost. Side note: I think I had this same compiler error message the first time I tried to use CLI arrays. The problem then had to do with name spaces.
Buck
|
|
|
|
|
Boy, this painting thing is really more trouble than its worth. The only way I can get my information to display is to open the file and then open a dialog box and drag it around the screen.
Buck
|
|
|
|
|
Hi Buck,
using a dialog box as an eraser ?
seems you forgot to call Invalidate() when your data has changed in such a way
that a (re)paint is necessary.
We discussed that a while back on some other thread...
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
Hi Luc,
Well I finally got this structured better in that I have a single OnPaint() function that calls the DisplayWaferMap() function and I am using Invalidate(myRegion) to repaint when necessary. It took me awhile to figure out 'myRegion = gcnew Drawing::Region(Screen::PrimaryScreen->Bounds);' to set the drawing region to the screen size. The downside to all of this is that the behavior of the application is unchanged.
|
|
|
|
|
Hi Buck,
1.
there is no need to specify a region to Invalidate(); if anything, its purpose is to
partially invalidate, i.e. cause a partial repaint. Setting it to the entire screen
does not make much sense, you could just leave the argument out then.
2.
No improvement?
I am pretty sure it now repaints automatically when things get covered then uncovered,
or minimized then restored; something your original code did not. That's why you had
to move the code from your menu item handler to the paint handler.
(And later you will appreciate if you would want to print !)
3.
So I guess your remaining worries are with speed. Maybe best thing to do is you show
the current paint code, give some context and speed estimates, so we can all have a look.
Greetings
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
|
Hi Luc, Everything Microsoft always seems to work the opposite of what you would expect.
1. The reason that I needed to specify a region (the entire screen) for invalidate is because without specifying the entire screen as a region the entire screen would be erased and only the area under the last control is painted. I tried using Update() since it says that its purpose is to redraw anything disturbed by the control but it did nothing.
2. Not in the time it takes to paint the array. If I remark out the function call that draws the array then everything is lightning quick. But if I dont and I bring up a dialog box of any size, when I try to move the dialog box it actually changes position about once a second (the time it takes to paint the array) wheather or not I have any graphics covered by the dialog box or not. And yes I am now delving into printing. The command seemokay enough but I can't figure out how to get my screen info into a document to print. I will be posting on this issue since I have found very little on code project or by googling for half a day.
3. The speed isn't that big of an issue for me, more curiosity as to why this is such a dog compared to MFC. I can send you a copy of the code if you email me where to send it. Side note: I have not received an email when my posts are replied to even though I have the box checked and just received an email confirmation from code project, so I don't know why answers to my posts do not email me.
I'm at brown@toko.com
Buck
|
|
|
|
|
Hi Buck,
1.
I will look into this, it sounds a mystery to me. I have never needed Update() at all,
and most often I don't specify a repaint rectangle or region.
2.
Seems like something still is not organized correctly. I look into that too.
Yes, printing on Windows is very strange at first; once you got it right for one app,
it becomes simple except for one aspect: predicting how many pages a document would take.
We can discuss this further, preferably after I had a chance to look into the other issues,
I would not want to add/modify printing code when the rest is still a bit shaky.
3.
Speed, even if not an issue, is getting my attention anyhow. Whatever the code, I want to
understand why it runs at the speed it runs, at what can be done to improve it.
I've sent you my coordinates, so we'll be in touch I guess.
Greetings
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
