C / C++ / MFC Discussion Boards

Re: check how many variable arguments are passed?

hansipet7-Jun-07 3:43

hansipet

7-Jun-07 3:43

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

Re: check how many variable arguments are passed?

CPallini7-Jun-07 3:57

CPallini

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.

Re: check how many variable arguments are passed?

hansipet7-Jun-07 4:03

hansipet

7-Jun-07 4:03

Thank you...I will check this..

Re: check how many variable arguments are passed?

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

Re: check how many variable arguments are passed?

hansipet7-Jun-07 5:46

hansipet

7-Jun-07 5:46

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

Re: check how many variable arguments are passed?

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

Hook Procedure not working when window is minimized

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

Re: Early Morning blues - Array of object pointers

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 />

Re: Early Morning blues - Array of object pointers

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]

Re: Early Morning blues - Array of object pointers

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,

Re: Early Morning blues - Array of object pointers

Cedric Moonen7-Jun-07 0:05

Cedric Moonen

7-Jun-07 0:05

My advice remains valid even if you found the bug Big Grin | :-D

. Why reinvent the wheel when something free exist ?

Cédric Moonen
Software developer

Charting control [v1.2]

String

mazeed6-Jun-07 22:53

mazeed

6-Jun-07 22:53

Hai i have some problem here.

1.

using namespace std;

int main()
{
char name[50];
char lastname[50];
char fullname[150];
char university[50];
char uni[100];
int age;

cout<<"Enter first name:";
cin.getline(name,50);
cout<<"Enter last name:";
cin.getline(lastname,50);
cout<<"Enter age:";
cin>>age;
cout<<"Enter University:";
cin.getline(university,20);
strcpy(fullname,name);
strcat(fullname, " ");
strcat(fullname,lastname);
cout<<"Your name:"<<fullname<<endl;
cout<<"your="" age:"<<age<<endl;
="" cout<<"study:"<<university<<endl;

}

2.

using="" namespace="" std;

int="" main()
{
="" char="" name[50];
="" lastname[50];
="" fullname[150];
="" university[50];
="" uni[100];
="" int="" age;

="" cout<<"enter="" first="" name:";
="" cin.getline(name,50);
="" last="" cin.getline(lastname,50);
="" university:";
="" cin.getline(university,20);=""
="" age:";
="" cin="">>age;
strcpy(fullname,name);
strcat(fullname, " ");
strcat(fullname,lastname);
cout<<"Your name:"<

Re: String

SandipG 7-Jun-07 1:21

SandipG

7-Jun-07 1:21

Try cin.ignore() or use fflush(stdin) to clear the buffer.

Re: String

mazeed7-Jun-07 14:50

mazeed

7-Jun-07 14:50

thank you so much......now i have an idea...
thank you Smile | :)

mazeed

Re: String

mazeed7-Jun-07 14:56

mazeed

7-Jun-07 14:56

thank you,
it is work..
i'm using cin.ignore()..
thank you so much... Big Grin | :-D

mazeed

Re: String

David Crow7-Jun-07 4:24

David Crow

7-Jun-07 4:24

Why are you using char[] variables with C++ when string variables would be way more efficient? Yeah, it's only a few hundred bytes, but that, coupled with not having to use strcxx(), is a good reason to switch.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Summation of numbers

LiYS6-Jun-07 22:50

LiYS

6-Jun-07 22:50

Hi all:

I'm wondering how's the following code snippet could finish returning the final 'nn' to the caller, since I did not explicitly return 'nn' on each recursive call.

int ss(int n)<br />
{<br />
    int nn;<br />
    if (n)<br />
        nn = (n + ss(n - 1));<br />
    else<br />
        return 0;<br />
}<br />
<br />
int n = ss(4);

Re: Summation of numbers

CPallini6-Jun-07 23:21

CPallini

6-Jun-07 23:21

Actually it returns 0 on my system. 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.

Re: Summation of numbers

prasad_som6-Jun-07 23:42

prasad_som

6-Jun-07 23:42

LiYS wrote:
I'm wondering how's the following code snippet could finish returning the final 'nn' to the caller, since I did not explicitly return 'nn' on each recursive call.

Compiler should issue warning about return path.

Prasad
MS MVP - VC++

Re: Summation of numbers

Rajkumar R6-Jun-07 23:45

Rajkumar R

6-Jun-07 23:45

I guess accumulator register is used to store the return value,
Since the code donot execute the return statement except at the last,
the previous result in the accumulator n+ss(n-1) is taken as return value.
Thus we get the currect value. If you used return 1; instead of return 0;
you get 1 + the result;

Best Regards
Raj

Re: Summation of numbers

LiYS7-Jun-07 0:50

LiYS

7-Jun-07 0:50

Yes, I guess you're right, add the following asm statement makes the program result logical to me. But what's the theory behind this?

int sum(int n)
{
    int nn;
    int dummy = 0;
    if (n)
    {
       nn = (n + sum(n - 1));
       __asm
       {
           mov eax, 0
       }
    }
    else
       return 0;
}

Re: Summation of numbers

Rajkumar R7-Jun-07 3:00

Rajkumar R

7-Jun-07 3:00

There is nothing theoritical, It depends on the implementation of the compiler.

if _asm::call is the opcode for a function call, then it has to place its return value in some register/memory location;

I guessed it is some where on the return mechanism and verified in code dissassembly.

int n = ss(4); will be something like
push 4
call ss
mov dword ptr [n],eax

After a call, we need the return value, called subroutine places its return value in eax.

Iam not sure, the theory of VC++ compiler is available open, but i believe this depends on the compiler implementation, for instance gcc compiler may not behave the same, hence most compiler flashes warning some thing like "not all code path returns value"

Best Regards
Raj

Re: Summation of numbers

Rajkumar R7-Jun-07 0:09

Rajkumar R

7-Jun-07 0:09

simply add some accumulator register involving operation next to nn = (n + ss(n - 1));
like another addition. It won't work as you expected.

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