C / C++ / MFC

Re: empty virtual method good practice question ...

11-Dec-02 9:26

Good question. Here's my answer:

1. Your AnotherDerivedClass::SomeMethod can always call DerivedClass::SomeMethod. If DerivedClass does not have it, the compiler will automatically call BaseClass's method.

2. You can certainly call BaseClass::SomeMethod from AnotherDerivedClass. (This isn't allowed in Java, by the way).

3. You only need to have a (dummy) DerivedClass::SomeMethod whenever you have another method of the same name with a different set of parameters. Here's the example:

void DerivedClass::SomeMethod()
{
  // nothing except calling base class.  
  BaseClass::SomeMethod();
}
 
void DerivedClass::SomeMethod(int nParam)
{
  // do something here
}

If you didn't have DerivedClass::SomeMethod() in DerivedClass, the compiler would not allow you to call DerivedClass::SomeMethod, either from AnotherDerivedClass or through an instance of the class.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Maximilien11-Dec-02 9:30

Maximilien

11-Dec-02 9:30

Alvaro Mendez wrote:
2. You can certainly call BaseClass::SomeMethod from AnotherDerivedClass. (This isn't allowed in Java, by the way).

I don't know Java ? so, in Java I'd have to call the base class method for each derive class ?

Alvaro Mendez wrote:
If you didn't have DerivedClass::SomeMethod() in DerivedClass, the compiler would not allow you to call DerivedClass::SomeMethod, either from AnotherDerivedClass or through an instance of the class.

Yep! that I know!

Thanks

Max.

Re: empty virtual method good practice question ...

Alvaro Mendez11-Dec-02 9:35

Re: empty virtual method good practice question ...

11-Dec-02 9:35

Maximilien wrote:
I don't know Java ? so, in Java I'd have to call the base class method for each derive class ?

Well, in Java you can only refer to the class to which you directly derived from, via the super keyword.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Maximilien11-Dec-02 9:38

Maximilien

11-Dec-02 9:38

Alvaro Mendez wrote:
Well, in Java you can only refer to the class to which you directly derived from, via the super keyword.

Sounds like Apple's ObjectC language, I have to look at ObjectiveC book tonight!

Max.

Char to INT?

Anonymous11-Dec-02 9:09

Anonymous

11-Dec-02 9:09

Hi.

I have a Char which containes a number, example 32. How do I convert the char to INT?

char cTest[100]="32";
int iTest;

now I want to convert the cTest to iTest so it's a integer instead of a char.

Any function which can do this?

thanks for any info.

Alvaro Mendez11-Dec-02 9:12

11-Dec-02 9:12

atoi.

int iTest = atoi(cTest);

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Nitron11-Dec-02 13:23

Nitron

11-Dec-02 13:23

i'll second that.

also, if you need a double, atof:

double data = atof(szData);

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Greven11-Dec-02 9:21

Greven

11-Dec-02 9:21

I think the easiest way would be to simply cast it...

iTest = (int)cTest[i];

Wouldn't that work? Unsure | :~

Programming in binary is as easy as 01 10 11.

Alvaro Mendez11-Dec-02 9:29

11-Dec-02 9:29

Nope, it wouldn't work. Only the first character would be converted, and to it's ASCII value -- which is not what he needs.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Greven11-Dec-02 10:23

Greven

11-Dec-02 10:23

Ah, my mistake... Didn't see the quote around 32... Thought he had an array of char's, not a string.
Blush | :O

Programming in binary is as easy as 01 10 11.

Christian Graus11-Dec-02 10:03

Christian Graus

11-Dec-02 10:03

I generally bring up a console project and test my theory if I'm not sure about advice I am about to give Smile | :)

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

C# will attract all comers, where VB is for IT Journalists and managers - Michael P Butler 05-12-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

Catching OnSysCommand in own class

Ravi Bhavnani11-Dec-02 9:39

Ravi Bhavnani

11-Dec-02 9:39

If you don't care about performance Smile | :)

you can do:

sscanf (cTest, "%d", &iTest);

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

In Place Server

Anthony988711-Dec-02 9:00

Anthony9887

11-Dec-02 9:00

I'm having troubles modifying the menus for the ole server once embedded into a container document.

Thanks

BtL2711-Dec-02 8:44

BtL27

11-Dec-02 8:44

Hi,

i think this problem may be easy to answer for you.

I have created my own class:

-header-file:

class CTrayIcon : public CWnd
{
public:
CTrayIcon(); // Konstruktor
virtual ~CTrayIcon(); // Dekonstruktor

int AddTrayIcon(HICON pIcon,int iMenu);
protected:
// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CTrayIcon)
//}}AFX_VIRTUAL
protected:
//{{AFX_MSG(CTrayIcon)
afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

The Class-Wizard automatically adds the function OnSysCommand to the header and of course to the cpp. Now, i do not know, what i must do, that all messages of the dlg-window(main-dialog-window), especially WM_SYSCOMMAND, can catch in my class ?

Re: Catching OnSysCommand in own class

Alvaro Mendez11-Dec-02 9:04

Type Libraries and MFC Question

11-Dec-02 9:04

beni27_27 wrote:
Now, i do not know, what i must do, that all messages of the dlg-window(main-dialog-window), especially WM_SYSCOMMAND, can catch in my class ?

I don't understand what you're asking; please clarify.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Nick Parker11-Dec-02 8:40

Nick Parker

11-Dec-02 8:40

I have written a .NET assembly that I want to use in MFC 6.0. According to an MSDN article[^], I need to use the Regasm.exe to make the necessary entries in the registry. I have gone ahead and done this using the following command to create a type library as well:

regasm mcpp.dll /tlb:mcpp.tlb

From what I understood, I then needed to reference the type library that is created one of two ways:

#import "mcpp.tlb" raw_interface_only

#import "mscorlib.tlb"
#import "mcpp.tlb"

I have done this however as soon as I try to compile following this it throws a slew of error within either mcpp.tlb or mscorlib.tlb, depending on which item I try (as I have tried both methods). Does anyone have any experience doing anything of this nature. Thanks

Nick Parker

Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein

Copying CString to char*

Like2Byte11-Dec-02 8:32

Like2Byte

11-Dec-02 8:32

Hi,

I need to output some CString data after I've copied it to a char array (ie: char ptrSomeCharArray[33]). I can't seem to get the data extracted from the CString object.

I've tried:

CString m_sFullname("Like2Byte"), m_sAccount("12345678"), m_sRoom("222");
char SomeCharArray[33];

sprintf( SomeCharArray + strlen(SomeCharArray), "%s", m_sAccount);
sprintf( SomeCharArray + strlen(SomeCharArray), "%s", m_sRoom);
sprintf( SomeCharArray + strlen(SomeCharArray), "%s", m_sFullname);

While this compiles without error, inserting it into a
MessageBox function displays garbage. Even wrapping the var in TEXT() doesn't work. I've also tried casting using LPCTSTR, LPTSTR and (const char*). None work correctly.

Anyone help out?

User 665811-Dec-02 8:43

User 6658

11-Dec-02 8:43

Have you tried e.g. sprintf( SomeCharArray + strlen(SomeCharArray), "%s", m_sAccount.GetBuffer(0)); ?

But err, what does the sprintf do? Do you want to append the CString to SomeCharArray? You should use strcat instead

regards

modified 12-Sep-18 21:01pm.

Like2Byte11-Dec-02 8:49

Like2Byte

11-Dec-02 8:49

Well, I tried m_sAccount.Mid(0) but that gave me the same results are m_sAccount.

Let me try your suggestion.
(The 'In a nut-shell' explination)sprintf basically copies whatever kind of data to end of another string converting it to a string when it's all done.
say, SomeCharArray contains "HelloWorld" and someIntValue = 32768.
Therefore, sprintf(SomeCharArray + strlen(SomeCharArray), "%i", someIntValue); copies 32768 to the end of SomeCharArray; thus, leaving, "HelloWorld32768".

(BRB)

Michael Dunn11-Dec-02 8:49

Michael Dunn

11-Dec-02 8:49

Any time you use a string object (CString or any other string wrapper class) with the printf family of functions, you need to cast the object to a pointer type, so that only the pointer is put on the stack.

sprintf( SomeCharArray + strlen(SomeCharArray), "%s", (LPCTSTR) m_sAccount);

But as Gregor said, the real bug in your code is how you construct the string in the first place. Just use one sprintf() call.

--Mike--
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Like2Byte11-Dec-02 8:51

Like2Byte

11-Dec-02 8:51

Of all the places I put (LTCTSTR), I *don't* think I placed it right there. Roll eyes | :rolleyes:

(BRB)

Alvaro Mendez11-Dec-02 8:56

11-Dec-02 8:56

You can use strcpy, like this:

strcpy(SomeCharArray, m_sAccount + m_sRoom + m_sFullname);

However, you need to be careful that the length of the 3 variables does not surpass the size of SomeCharArray - 1.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)