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I'm trying to learn using "Sams Teach Yourself Visual C++ 6 in 21 Days". Has anybody read that? I'm finding that there are a lot of mistakes in the sample code in the book. For example, I took this code exactly out of the book:
void CDialogsDlg::OnYesnocancel()
{
// TODO: Add your control notification handler code here
int iResults;
iResults = MessageBox("Press the Yes, No, or Cancel button", "Yes, No, Cancel Dialog",
MB_YESNOCANCEL | MB_ICONINFORMATION);
switch(iResults)
{
case IDYES:
m_sResults = "Yes! Yes! Yes!";
break;
case IDNO:
m_sResults = "No, no, no, no, no.";
break;
case IDCANCEL:
m_sResults = "Sorry, canceled.";
break;
}
UpdateData(FALSE);
}
and I got these errors:
--------------------Configuration: Dialogs - Win32 Debug--------------------
Compiling...
DialogsDlg.cpp
C:\Windows\Desktop\Dialogs\DialogsDlg.cpp(185) : error C2065: 'm_sResults' : undeclared identifier
C:\Windows\Desktop\Dialogs\DialogsDlg.cpp(185) : error C2440: '=' : cannot convert from 'char [15]' to 'int'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast
C:\Windows\Desktop\Dialogs\DialogsDlg.cpp(188) : error C2440: '=' : cannot convert from 'char [20]' to 'int'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast
C:\Windows\Desktop\Dialogs\DialogsDlg.cpp(191) : error C2440: '=' : cannot convert from 'char [17]' to 'int'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast
Error executing cl.exe.
DialogsDlg.obj - 4 error(s), 0 warning(s)
Am I forgetting to do something, because I've doubled checked the code and its exactly what appears in the book. This is happening to me for every single code in the book. Can anybody recommend a better book?
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It looks to me like m_sResults is a member variable, probably a CString mapped in classwizard to an edit box or a static control or something.
What does that mean? well, you can add an edit box to your dialog in the dialog editor. You've probably already learned that in VC/MFC, a dialog is represented by a class. well, each control on the dialog box is represented by a member variable in that class. you use the class wizard tool to control the mappings between controls on the dialog, and memebr variables in your class.
The code snippet you've typed in relies on this class wizard mapping being setup: if it was, you wouldnt be getting those errors.
I think therefore that the code you are reading is meant to be indicative of the point in discussion and not directly intended to be typed in and tried. It probably isn't necessary for the book to explain how to make every classwizard mapping for every control in every example.
If there's a CD in the book, it probably has VC projects to open of all these code snippets, so you can see the code in action. These projects will include all of the dependant configuration that is omitted from the sample.
Stick at it, and if you get stuck, post here... people will help.
You'll feel very rewarded when you write your first working MFC app on your own. But I warn you now, the 21 days thing is a gimmick... it takes years to learn VC++ properly. The really knowledgeable people on this forum have all been using VC for years, and I bet if you asked any of them they'd tell you they're still learning.
Jon
Sorry to dissapoint you all with my lack of a witty or poignant signature.
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just forgot to say thank you
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Please stop including your whole project every time you have a problem.
And spending some more time describing what the problem is would help too 
:\Windows\Desktop\DataStru\main.cpp(639) : error C2664: 'binarySearch' : cannot convert parameter 1 from 'class Stock *(void)' to 'class Stock *' There is no context in which this conversion is possibleError executing cl.exe.main.obj - 1 error(s), 0 warning(s)
on line 639, cast your parameter 1 to (Stock *).
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You missed a ; - or did you. Use MSDN, and then you would leard the following :
'function' : cannot convert parameter number from 'type1' to 'type2'
The following is an example of this error:
class A {} a;
func( int, A );
void main()
{
func( 1, 1 );
}
It just gets on my tits. Do some investigation and try an narrow the problem down by say - commenting out code!!!!!! And seeing if it still recompiles, unless you wrote all of this with out one build.
Don't let me see you post a stupid question with all this code again.
Giles
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I'll just add my voice to the people saying you should take a closer look yourself before posting, and at the least show you've done that by only posting the offending code instead of half your project, and describe your problem a bit.
However,
return -(first +1); //failed to find
why are you returning a range of numbers to indicate failure ? Usual practice is to return -1. what if a client of this function accidentally sends a range that starts at -3 ? You're not doing any range validation ( i.e. checking for valid values to be passed in ), which makes all of this code very fragile.
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
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I have an embedded Visual C++ program, which uses the Imgdecmp.dll to load and display JPEG images.
Zooming is achieved through a variable contained in the Decompress Image Structure (an int between 1 and 100). This works fine, however the map needs to be reloaded (via the open file dialog everytime the user zooms in or out)to show the zoom effect.
Does anyone know a way around this...any suggestions greatly appreciated.
Cheers,
Colm
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Hello,
I am not able to include any class derived from CListView or CTreeView in my project for say a child view of some sort.
I get error saying the class is undefined.
I can however make a new project with either of the views by selecting the right choice in the app wizard.
Why?
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You need to include:-
#include <afxcview.h>
Personally, i'd add that to StdAfx.h
This is a frequent problem: many of the MFC classes are defined in header files not included by default. Whenever you choose a new class or function or whatever, if you look at the class overview page in MSDN, it tells what what header file to use. Make sure you add suitable includes for this header file.
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as title, my win32 program(just use API) can run in VC 6
but can't in BCB 5.0, why?
just a simple api function MessageBox() also can't show anything
hi
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Compile?
How do you are compiling the project?
Regards....
The programmer's national anthem is 'AAAAAAAARRRRGHHHHH!!'.
Carlos Antollini.
Sonork ID 100.10529 cantollini
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i'm sorry , may be there is something wrong with my expression,
that is, my code can't run in bcb 5.0 buy can in vc 5.0.
for example, the MessageBox() can't work!
hi
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But Does your code Compile, or not?
Regards...
"The three most dangerous things in the world are a programmer with a soldering iron, a hardware type with a software patch and a user with an idea."
Carlos Antollini.
Sonork ID 100.10529 cantollini
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like this:
#include<windows.h>
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
MessageBox(NULL, TEXT("hello"), TEXT("caption"), 0);
return 0;
}
it can run in VC,buy can't in BCB 5
why?
hi
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Some time ago I remember seeing an example of how to do a clrscr() in VC, without using system("cls") way. But now I can't find the example/program anywhere... Are there someone out there who can help me find this example again?
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the function is _clearscreen(_GCLEARSCREEN);
Is declared in graph.h
Regards
There are two ways to write error-free programs; only the third one works.
Carlos Antollini.
Sonork ID 100.10529 cantollini
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#define PERR(bSuccess, api){if(!(bSuccess)) printf("%s:Error %d from %s \
on line %d\n", __FILE__, GetLastError(), api, __LINE__);}
void cls( HANDLE hConsole )
{
COORD coordScreen = { 0, 0 }; /* here's where we'll home the
cursor */
BOOL bSuccess;
DWORD cCharsWritten;
CONSOLE_SCREEN_BUFFER_INFO csbi; /* to get buffer info */
DWORD dwConSize; /* number of character cells in
the current buffer */
/* get the number of character cells in the current buffer */
bSuccess = GetConsoleScreenBufferInfo( hConsole, &csbi );
PERR( bSuccess, "GetConsoleScreenBufferInfo" );
dwConSize = csbi.dwSize.X * csbi.dwSize.Y;
/* fill the entire screen with blanks */
bSuccess = FillConsoleOutputCharacter( hConsole, (TCHAR) ' ',
dwConSize, coordScreen, &cCharsWritten );
PERR( bSuccess, "FillConsoleOutputCharacter" );
/* get the current text attribute */
bSuccess = GetConsoleScreenBufferInfo( hConsole, &csbi );
PERR( bSuccess, "ConsoleScreenBufferInfo" );
/* now set the buffer's attributes accordingly */
bSuccess = FillConsoleOutputAttribute( hConsole, csbi.wAttributes,
dwConSize, coordScreen, &cCharsWritten );
PERR( bSuccess, "FillConsoleOutputAttribute" );
/* put the cursor at (0, 0) */
bSuccess = SetConsoleCursorPosition( hConsole, coordScreen );
PERR( bSuccess, "SetConsoleCursorPosition" );
return;
}
IMO never seen any clrscr() type function in VC.
The above will help you to clear the console.
Atul
Sonork ID : 100.13714 netdiva
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Hi,
I am developing a VC++ application in which I have a dialog (Class corresponding to it say CDialog1).
I have a pointer of this dialog class (CDialog1 * myDlg) as a member in the Application Class.
I am bringing up this dialog when one of the menu item of the application is clicked.
In this dialog's OnClick( ) event of a button I am destroying its pointer (that is destroying myDlg variable). Further in the OnClick() function I have a Messagebox to be populated with some value. We see the message box is displayed.
Can anyone explain me how this happens, even though I am destroying the object of the class the rest of the function code is executed how. I have a feeling that its something to do with the event handling?
Please reply back to my mail id.
TIA,
Rgds,
Vikas.
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Let me be sure I'm understanding you. Your have a dialog object dynamically created, pointed to by (CDialog *myDlg) and inside a member function of that dialog, you're (delete myDlg)'ing it?
If I'm right, then that leads to two points:
1. Why?
2. IIRC an object trying to delete itself is "undefined" behaviour.
Sorry to dissapoint you all with my lack of a witty or poignant signature.
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Here goes:-
I have an application where one dialog is active at a time.
I want to destroy the active dialog on the click of a button present on that dialog and bring up another dialog.
The surprising thing here is that in the function OnClick( ) the destructor of the dialog is called first as I am deleting the dialog pointer and then the remaining part of the code is executed.
What is nagging me is how this is possible that even after deleting the dialog a member function of that dialog is still executing ??
I am enclosing the code to make my point clearer:
void CDialog1::OnButton1()
{
theApp.myDlg->DestroyWindow();
delete(theApp.myDlg); //Destructor is called at this point
theApp.myDlg = NULL;
AfxMessageBox("This function is continued after the destructor");
}
Here the message box should not be displayed, but surprise surprise !!
The message box is displayed and the application works fine.
Any answers ??
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Don't try and delete the dialog from within the dialogs member function.
As a rule of thumb, and yes, there ARE many exceptions, but you should delete an object in the same block as you new'ed it in the first place. unless you specifically want the object to remain in existence once that code block is out of scope.
What you should do is this...
Your "theApp" object is the object that created the dialog, and called DoModal() on it. Since the dialog is modal, that thread blocks until the dialog closes.
Try something like this:
CMyWinApp::Whatever()
{
CDialog1 *myDlg;
CDialog2 *myDlg2;
BOOL bShowDlg1=TRUE;
do {
if (bShowDlg1) {
myDlg = new CDialog1;
myDlg.DoModal();
delete myDlg;
bShowDlg1=FALSE;
} else {
myDlg2 = new CDialog2;
myDlg2.DoModal();
delete myDlg2;
bShowDlg1=TRUE;
}
} while (TRUE);
}
Then, in your dialogs:
CDialog1::OnClick()
{
PostMessage(WM_CLOSE,0,0);
}
I expect you'll need to modify that to meet your exact needs. But you should take the pertinant points, that being to close the dialog with PostMessage() and have the parent object handle allocation and deallocation of the dialog.
Jon
Sorry to dissapoint you all with my lack of a witty or poignant signature.
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When you destroy an object you delete the struct which keeps the member variables and the VTABLE. You don't "delete" the implementation of the member functions. A method of an object is a function with the "this" calling convention ( the "this" pointer is passed to the function thru the ECX register). So the behavior is as expected.
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That explains things nicely.
Personally, i can't think of any real world situation where an object should delete itself. Can anyone point one out?
Sorry to dissapoint you all with my lack of a witty or poignant signature.
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Think technique is used ( for example )when you implement COM objects and the last reference to the object is released :
ULONG MyObject::Release()
{
if( -- m_dwCount == 0 )
{
delete this;
}
return m_dwCount;
}
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In what you have explained above, are we violating any thing or is it a perfectly acceptable implementation?
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