C / C++ / MFC

6-Jun-07 23:47

Is it possible to check how many variable arguments are passed to a function?

Best regards
Hansjörg

BadKarma6-Jun-07 23:49

BadKarma

6-Jun-07 23:49

No, when using ellipsis to pass arguments you should always give the number of arguments,
or a way to get them like sprintf.

codito ergo sum

Roger Stoltz7-Jun-07 0:29

Roger Stoltz

7-Jun-07 0:29

Have a look here[^].

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

hansipet7-Jun-07 0:58

7-Jun-07 0:58

May be that I have missed something. but here I don't can find something about the number of arguments...

CPallini7-Jun-07 1:39

7-Jun-07 1:39

The sample shows how you can implement functions with a variable number of arguments using C.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

hansipet7-Jun-07 2:38

7-Jun-07 2:38

HOw this works I know. But I need a way to know the number of variable arguments. Because if no one are used, I want to optimize the function...it's a lot faster.

Best regards
Hansjörg

CPallini7-Jun-07 2:59

7-Jun-07 2:59

if optimization is your concern, then avoid to use variable number of arguments (or use a mechanism such as the main one, i.e. an array of arguments and its length passed to your function).

BTW, referring to the MSDN sample (link given by Roger Stoltz) [^], nothing prevents you to use the marker to indicate the total number of arguments: does this fit your needs?

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

hansipet7-Jun-07 3:13

7-Jun-07 3:13

The marker is not so a good was i think...
The problem is that it is not possible to define 2 methods in a class (same name). One with variable length parameter and one without...This would be the best solution for me too...

I want to make a logger class in this way...

class Logger{
void Log(LPCSTR format,...);
void Log(LPCSTR message);
}

something like that. It is easier for the user to have allways the same name...Do you know any solution for that? arrays are also not so good..it's not easy to use...

if not I have to give the function another name.... Frown | :(

Best regards

hansjörg

CPallini7-Jun-07 3:24

7-Jun-07 3:24

hansipet wrote:
Do you know any solution for that?

No.

BTW, why don't you emulate the behaviour of cout instead of the one of printf?

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

hansipet7-Jun-07 3:43

7-Jun-07 3:43

This would be a great solution...but how I can do this?

CPallini7-Jun-07 3:57

7-Jun-07 3:57

The tricky part is customizing the >> operator. Have a look, for instance, at this article http://www.codeproject.com/cpp/Encoder.asp[^].
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

hansipet7-Jun-07 4:03

7-Jun-07 4:03

Thank you...I will check this..

Roger Stoltz7-Jun-07 4:03

Roger Stoltz

7-Jun-07 4:03

If you're using this for logging purposes, why don't use CString::FormatV()?
Like this:

void <YourClassName>::Log( LPTSTR pText, ... )
{
    CString LogText;
    va_list args;
    va_start( args, pText );
    LogText.FormatV( pText, args );

    // Do whatever you want with the LogText...
}

This would make the function call similar to printf().

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

hansipet7-Jun-07 5:46

7-Jun-07 5:46

I think this is in the MFC library and I don't can use it...

Hook Procedure not working when window is minimized

Roger Stoltz7-Jun-07 6:42

Roger Stoltz

7-Jun-07 6:42

hansipet wrote:
I think this is in the MFC library and I don't can use it...

Ok, then use vsprintf(). See here[^].
It works the same as the CString alternative, but in this case you have to provide the output buffer.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Jayapal Chandran6-Jun-07 23:41

Jayapal Chandran

6-Jun-07 23:41

Problem : my hook procedure is not working when the main window losts focus or minimized...

description:
i have written a global hook procedure to track the keystrokes. the hook procedure resides in a dll and i am calling it from the main window. from the dll i am displaying the keycode using a messagebox. it is working globally... then problem is when i tried to write the keypress to a file it is working but when the main window losts focus the keystrokes are not written to the file but it displayed... i tried to pass the value to the main window using WM_COPYDATA but neither of the options helped... i was able to reveice the WM_COPYDATA message in the main window only when the window is active and when my window goes inactive it dosent work... how to solve this... i am using dev C++ ide... i am using C style and not c++ or MFC...what should be done to make the main window always receive messages from the hook procedure???

Managing Bitrate through Programming

Andy Rama6-Jun-07 23:22

Andy Rama

6-Jun-07 23:22

Hi to All,
How to manage Bitrate through Programming?

In my application during runtime, I am generating some data & transfering it to (any type of) Output (like IP Output, any type of Output Card, or writting a File). I have done it, but I want to transfer data at particular Bitrate to the Output.

Consider that I am sending generated data to IP, so how I can achieve it's transfer at particular bitrate?
When I was trying to transfer data at 2Mbps OR 3Mbps using MachineCycles & Sleep(1) at getting output bitrate as 749 Kbps with 1% Processing. But when I remove Sleep(1) I am getting out bitrate as 1.9Mbps OR 2.9 Mbps (respectively), with 61% of Procssing.

What is the solution to achieve bitrate transfer with low Processing?

Early Morning blues - Array of object pointers

mcsherry6-Jun-07 22:57

mcsherry

6-Jun-07 22:57

In my program I've got a base class (all member methods are pure virtual) which a number of classes are derived from. In a seperate class I want to have an array which contains pointers to these classes, i.e. it doesn't create the objects just has a pointer to them. My code loks like this so far:

<br />
class BaseClass<br />
{<br />
public:<br />
  BaseClass( ) ;<br />
  <br />
  virtual<br />
  ~BaseClass( ) ;<br />
<br />
  virtual void<br />
  EveryClassNeedsThis ( ) = 0 ;<br />
<br />
private:<br />
  BaseClass( const BaseClass &source ) ;<br />
  <br />
  BaseClass& <br />
  BaseClass::operator= ( const BaseClass &rhs ) ;<br />
<br />
} ;<br />
<br />
class DerivedClassA : public BaseClass<br />
{<br />
public:<br />
  DerivedClassA ( ) ;<br />
  <br />
  virtual<br />
  ~DerivedClassA ( ) ;<br />
<br />
  void<br />
  EveryClassNeedsThis ( ) ;<br />
<br />
private:<br />
  DerivedClassA ( const DerivedClassA &source ) ;<br />
  <br />
  DerivedClassA & <br />
  DerivedClassA ::operator= ( const DerivedClassA &rhs ) ;<br />
} ;<br />
<br />
class ArrayClass<br />
{<br />
public:<br />
  ArrayClass ( ) ;<br />
  <br />
  virtual<br />
  ~ArrayClass ( ) ;<br />
  <br />
  void<br />
  AddToArray ( BaseClass *obj )<br />
<br />
private:<br />
  ArrayClass( const ArrayClass &source ) ;<br />
  <br />
  ArrayClass& <br />
  ArrayClass::operator= ( const ArrayClass &rhs ) ;<br />
<br />
  BaseClass *m_DerivedObjects ;<br />
} ;<br />

In the implementation for AddToArray I have

<br />
{<br />
  m_DerivedObjects = obj ;<br />
}<br />

but i get an access violation on this, so can anyone spot what I'm doing wrong? Sigh | :sigh:

TIA,
Andy

mcsherry6-Jun-07 23:00

mcsherry

6-Jun-07 23:00

morning blues even worse than I thought!

<br />
void<br />
AddToArray ( BaseClass *obj,<br />
             int pos )<br />
<br />
BaseClass *m_DerivedObjects<br />

should be

<br />
BaseClass *m_DerivedObjects [10] ;<br />

and

 <br />
m_DerivedObjects = obj ;<br />

should be:

<br />
m_DerivedObjects [pos] = obj ;<br />

Cedric Moonen6-Jun-07 23:08

Cedric Moonen

6-Jun-07 23:08

If you want to manipulate an array of objects (or pointers to objects if you want to use polymorphism), I highly suggest that you take a look at the container classes from the STL: vector, list, ...
Everything has been implemented and has been used by a lot of developers, so, chances of bugs are close to zero.

Cédric Moonen
Software developer

Charting control [v1.2]

mcsherry6-Jun-07 23:45

mcsherry

6-Jun-07 23:45

Hi,

thanks for your reply, found out it wasn't the array causing the problem but that I was calling a non static method in a non-static manor (also the variables are not static either). D'Oh! | :doh:

cheers,