Re: random NUmbers - C / C++ / MFC Discussion Boards

Rage11-Jul-02 22:12

11-Jul-02 22:12

This problem comes from a bad update of the .ncb file.

Send me a mail, and i´ll mail you back the OpenVC dll which installs an add-in in VC++ (a button which erases .NCB file and reopens your windows). It is very easy to do, and kicks ass.

~RaGE();

Re: System Busy...

Brad Bruce11-Jul-02 10:04

Brad Bruce

11-Jul-02 10:04

This is what I use...

BOOL DoEvents()
{
        MSG msg;
        while ( ::PeekMessage( &msg, NULL, 0, 0, PM_NOREMOVE ) )
        {
				if ( !AfxGetApp()->PumpMessage( ) )
                {
                        ::PostQuitMessage( 1 );
                        return FALSE;
                }
        }
        // let MFC do its idle processing
        LONG lIdle = 0;
        while (AfxGetApp()->OnIdle(lIdle++ ) )
                ;
        return TRUE;
}

doble to String...

Speedy11-Jul-02 9:37

Speedy

11-Jul-02 9:37

Is there any simple method to convert from double to CString(i have seen _ecvt(),_gcvt(),_fcvt() but too complex )i need something like Javas .toString(1234.4432) method.
THANX

Re: doble to String...

Joaquín M López Muñoz11-Jul-02 9:44

Joaquín M López Muñoz

11-Jul-02 9:44

Check for the Format member function for CStrings.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

random NUmbers

ib04212911-Jul-02 9:37

ib042129

11-Jul-02 9:37

Ok, here's the deal.
I got an "array" of 60 normal variables
and a separate "array" of 10 filler (fake) variables
I need to go through the "array" of 60 and
as I do I need to randomly place all the variables
of the "array" of 10 between some of those of the first array

if I just do something like if(rand()%(60/10))
use normal;
else
use filler;

I might not get all ten variable in. What algorythm should I use
to randomly run each of the 10 variables between the 60 normal ones, and to make sure I do not get a systematic large chunk of normal variables?

P.S. I don't know if what I said is very clear, sorry about that....

Re: random NUmbers

Joaquín M López Muñoz11-Jul-02 9:53

Joaquín M López Muñoz

11-Jul-02 9:53

Something like this should work:

int fillers_used=0;
for(int i=n;i<60;++i){
  if(fillers_used<10 && rand()%((60-i)/(10-fillers_used))) {
    //use normal
  }
  else{
    // use filler
    ++fillers_used;
  }
}

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: random NUmbers

ib04212911-Jul-02 10:07

ib042129

11-Jul-02 10:07

Thanks a lot...
but this way wouldn't the frequency of the filler used be increased as I go through the array?
(nnnnnnnnfnnnnnnnfnnnnnfnnnnfnnfnnff)?

Re: random NUmbers

Joaquín M López Muñoz11-Jul-02 11:09

Joaquín M López Muñoz

11-Jul-02 11:09

Well there's a deficiency due to truncation problems, I guess you should use something like this instead:

static double rand01()
{
  int r;
  while((r=rand())==RAND_MAX);
  return (double)rand/RAND_MAX;
}
...
if(rand01()<(double)(10-fillers_used)/(60-i)){
...

Apart from this, the process is unbiased. To prove this, we can use a little probability. Let's call P_n the probability that the process uses a filler value at position n. Also, let p=10/60, q=1-(10/60).Then:

P₀ = 10/60
P₁ = P₀·(9/59)+(1-P₀)·(10/59) = (10/60)·(9/59)+(50/60)·(10/59) = 590/3540 = 10/60
P_n = pⁿ·((10-n)/(60-n)) + p^n-1·q·((10-(n-1))/(60-n)) + ··· + qⁿ·(10/(60-n))

It can be formally proven that P_n = 10/60 for every n, but also a small test program doing the calculations will convince you.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

How to show File Preview in the Windows Explorer.

Ganesh Agrawal11-Jul-02 9:18

Ganesh Agrawal

11-Jul-02 9:18

I have an application written in MFC. The document data of the application contains the File Preview as form of Bitmap.
I show the File Preview in the File Open dialog of my application.

Now I want to enhance this to show the Thumbnail File Preview when the user selects the File in Windows Explorer. This is similar to what the .BMP & .JPEG File does. How can I make the OS aware and as to where the OS can look the File Preview in the File.

Thanks

Re: How to show File Preview in the Windows Explorer.

KaЯl12-Jul-02 5:01

KaЯl

12-Jul-02 5:01

"thumbnail preview" is based on .HTT template and a preview activeX. There's a good article on MSDN about this. Have a look to "More Windows 2000 UI Goodies: Extending Explorer Views by Customizing Hypertext Template Files" , msdn.microsoft.com/msdnmag/issues/0600/w2kui2/w2kui2.asp

HTH,

We do not inherit the Earth from our ancestors. We borrow it from our children.

Antoine de Saint Exupéry (1900-1944)

Re: How to show File Preview in the Windows Explorer.

Ganesh Agrawal12-Jul-02 6:25

Ganesh Agrawal

12-Jul-02 6:25

Thanks Karl.
I shall investigate & let you know after I have implemented it.

Wrong return type from CObList (newb question)

EBerlin11-Jul-02 8:25

EBerlin

11-Jul-02 8:25

ok I have a pointer to a COblist
CObList* m_Unsorted_Members = GetDocument()->Get_Unsorted();

and im inserting members of the class State. The State Class is inherited from CObject since CObList only takes CObject type.

Container = new State(Name, Loc, pop, area);
m_Bookmark = m_Unsorted_Members->AddTail(Container);

all is good
however when I try and retrieve a member from the list
State* pObject = m_Unsorted_Members->GetAt(m_Bookmark);

I get an error saying that it cant convert from type CObject* to State*
Why is GetAt(m_Bookmark) not returning the same type that I inserted and instead is returning the base class?

thanks in advance,
Eric

Problem Fixed

EBerlin11-Jul-02 8:30

EBerlin

11-Jul-02 8:30

Ok I just fixed my own problem (about 2 min after I wrote this post of course)

needed to add

State* pObject = (State*) m_Unsorted_Members->GetAt(m_Bookmark);

Is that extra code converting from base class to child class? I dont exactly understand the functionality of it.

Either way code works now

Re: Wrong return type from CObList (newb question)

jbarton11-Jul-02 9:12

jbarton

11-Jul-02 9:12

Instead of using CObList directly, you should use CTypedPtrList to make the list typesafe. You can put any pointer which is derived from CObject into a CObList. You also need to cast the value when you take it out of a CObList (which again could lead to errors if the actual pointer is not the type that you are casting it to).

To use CTypedPtrList to contain pointers to State objects, you can declare it as follows:

CTypedPtrList<CObList,State *> stateList;

This list works the same as CObList, except that you can only put State * objects into the list, and any objects you get from the list are State * objects.

So, this works:

m_Bookmark = stateList.AddTail( new State(Name,Loc,pop,area) );

And, this works:

State *pObject = stateList.GetAt( m_Bookmark ); // note: no cast

Best regards,
John

Re: Wrong return type from CObList (newb question)

EBerlin11-Jul-02 10:55

EBerlin

11-Jul-02 10:55

Thanks for your response. The reason I chose not to make the list typesafe is because I am under the impression that it is more dificult to perform serialization on lists of it is a CTypedPtrList. This is my first time performing serialization using MFC's DOC/VIEW structure as opposed to straight writing to text files.

Was my information correct or is serialization identical for both types of lists?

Re: Wrong return type from CObList (newb question)

jbarton15-Jul-02 2:08

jbarton

15-Jul-02 2:08

You should have no problems with serialization of CTypedPtrList. It is a simple wrapper class for whatever list type is passed as the first argument. Since CObList is being passed as the first argument, it supports serialization the same way as CObList. If you passed a CPtrList as the first argument, it wouldn't support serialization, as serialization isn't supported by CPtrList.

Best regards,
John

OLE??

Kuniva11-Jul-02 7:52

Kuniva

11-Jul-02 7:52

uh whats OLE? whats does it mean? whats the concept? in short: what is it????
I see a lot about OLE controls and all but whats specific about OLE? and is it good?

Kuniva
--------------------------------------------

Re: OLE??

Anonymous11-Jul-02 8:04

Anonymous

11-Jul-02 8:04

stands for Object Linking and Embedding. is a COM based technology and a precursor for activex technology. the older version of OLE which was first used to embed office documents in other documents(like an Excel sheet in a Word doc) and later eveolved into activex/COM/DCOM.

Getting DevStudio dependencies correct

Jonathan Gilligan11-Jul-02 7:47

Jonathan Gilligan

11-Jul-02 7:47

I am working on a project in CWeb, where I work on a source file foo.w, which is then compiled by a custom build step to produce foo.c, foo.h, and foo.tex. I include foo.c, foo.h, and foo.tex in my project, and use the basic C compiler settings to control the compilation of the .c files and another custom build rule to control the compilation of the documentation foo.tex to foo.pdf.

Here is where I get into trouble. A makefile would have no problem understanding that foo.tex depends on foo.w and that foo.pdf depends on foo.tex, so if foo.w has been changed, a build must FIRST compile foo.w to foo.tex and THEN compile foo.tex to foo.pdf.

I can't seem to get DevStudio to understand this, so when I edit foo.w and hit build, it first compiles foo.tex to foo.pdf and then compiles foo.w to foo.tex!. Any thoughts? This is analogous to things people must also have gone through working with Bison and Flex in DevStudio.

Bomb our homes and threaten our children, and, as difficult as it is, we will still love you --- Martin Luther King, Jr.

Re: Getting DevStudio dependencies correct

J Patel11-Jul-02 11:48

J Patel

11-Jul-02 11:48

Hi,

Why not create 2 different projects and just have foo.w in one and the other files in the other project. You can then set project dependencies to have the second project (the one with .c,.h and .tex) files to be dependent on the first one. So, when you hit build it will compile the first project (seeing your .w has changed) and then compile the second one (with the newly generated files).

I've never worked with Bison and Flex but this may work..

HTH

Jignesh

ACtiveX Guru's...

Anonymous11-Jul-02 7:29

Anonymous

11-Jul-02 7:29

I developed two activex controls, in two seperate projects. Is there an easy way to combine them, so that when the project builds I get two seperate ocx's.

Thanks in advance...

Re: ACtiveX Guru's...

Bill Wilson11-Jul-02 11:56

Bill Wilson

11-Jul-02 11:56

Say your two controls are Actrl and Bctrl

Open the Actrl project.
Select Insert project into workspace from the Project menu.
Choose the Bctrl project.
Select Dependencies from the Project menu.
Check the Bctrl project.

When ever you build Actrl, Bctrl will also be built if it has changed. A Rebuild all will do both.

A variation of this is to create a wrapper project and add both controls to it.

Array of structure

Richard Jones11-Jul-02 7:29

Richard Jones

11-Jul-02 7:29

I am currently storing many separate arrays of different variable types.
ie CArray<cstring, cstring=""> id;
CArray<cstring, cstring=""> address;
CArray<uint, uint=""> type;
CArray<cstring, cstring=""> label;
CArray<lpdispatch, lpdispatch=""> shape;
CArray<cstring, cstring=""> mapno;

When I delete an item, I have to delete it from all other arrays.

I would like to store one array of all the items.

How would I define this: as a class or a struct?

Would I then use CArray<class, class=""> to store the collection? Confused | :confused:

Thank you for any help.

Re: Array of structure

Nish Nishant11-Jul-02 7:38

Nish Nishant

11-Jul-02 7:38

Do something similar to :-

struct mystruct
{
public:
    UINT id;
    CString address;
    CString type;
    CString label;
    UINT shape;
    UINT mapno
};

Now have a CArray of mystructs

Regards
Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Array of structure

Christian Graus11-Jul-02 12:06

Christian Graus

11-Jul-02 12:06

Richard Jones wrote:
Would I then use CArray to store the collection?

You'd do better to use std::vector because it is inherently superior to CArray, which was written only to be a stopgap until vector arrived. Check out my article on vector here on CP.

Christian

come on all you MS suckups, defend your sugar-daddy now. - Chris Losinger - 11/07/2002

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