C / C++ / MFC

21-May-02 5:25

I want to write a function that return CList and items in CList is CString.I declare it in these two way but I get some errors.

CList FindFile(LPCTSTR directorypath);

CList<cstring ,="" cstring&=""> FindFile(LPCTSTR directorypath);

What is the correct way for it?

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

Paul M Watt21-May-02 5:34

Paul M Watt

21-May-02 5:34

I would return a CList* rather than the CList to prevent the entire list from being copied into a temporary variable, you will simply return the address of the CList.

Also, is there a problem in your declaration of the CList that you are using, I think that there may be a CStringList class that you can use that is predefined in MFC.

One more suggestion is to possibly think about dumping the inferior Micorsoft containers and switching to STL.

Good luck!

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Mazdak21-May-02 5:58

21-May-02 5:58

kilowatt wrote:
I think that there may be a CStringList class that you can use that is predefined in MFC.

Now I use this one,But I get error in the RETURN statement of my function:

error C2558: class 'CStringList' : no copy constructor available or copy constructor is declared 'explicit'

Any Suggestion?

Thanks Smile | :)

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

ISEffects - effects for images

C^hris L^osinger21-May-02 6:00

C^hris L^osinger

21-May-02 6:00

return "CStringList *" or "CStringList &"
-c

The ants are my friends. They're blowing in the wind.

Mazdak21-May-02 6:14

21-May-02 6:14

Thanks

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

perlmunger21-May-02 5:43

perlmunger

21-May-02 5:43

If you are trying to return a CList as opposed to a CList*, you're going to have trouble. You have two choices here:

1. Send in the address of or a reference to the CList like so:

BOOL FindFile( LPCTSTR directorypath, CListCList<TYPE_LIST>* list )
{
    // Populate list using the pointer operator ->
}

// Implementation

CList<TYPE_LIST> myList;
if( !FindFile( "bob.txt", &myList ) )
{
    // Notify user, etc.
}

BOOL FindFile( LPCTSTR directorypath, CList<TYPE_LIST>& list )
{
    // Populate list using the dot operator .
}

// Implementation

CList<TYPE_LIST> myList;
if( !FindFile( "bob.txt", myList ) )
{
    // Notify user, etc.
}

2. The other way you can do this is by creating your CList with new inside the function like this:

CListCList<TYPE_LIST>* FindFile( LPCTSTR directorypath  )
{
    // Create the list with new
    CListCList<TYPE_LIST>* myList = new CListCList<TYPE_LIST>();
    // Populate list using the pointer operator ->
    .
    .
    .
    return myList;

}

// Implementation

CList<TYPE_LIST>* list = FindFile( "bob.txt" );
// Do something with list
.
.
.
// Empty out the list
list->RemoveAll();
// Delete the list
delete list;

You must call delete on the list if you do it this last way or you'll have a memory leak.

Hope this helps.

-Matt

------------------------------------------

The 3 great virtues of a programmer:
Laziness, Impatience, and Hubris.
--Larry Wall

Mazdak21-May-02 6:01

Re: how using PTSTR type?

21-May-02 6:01

Thank you very much Matt.It is very helpful. Smile | :)

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

extern "C"

21-May-02 5:26

I was under the impression that you usually use extern "C" when you are trying to access code in other languages from C++..but I have also noticed that extern "C" is used sometimes within C++ to call various functions especially in a lot of DLLs..

For instance, the other day I came across a piece of code where you had a dialog resource in one separate DLL project and an MFC Doc/View exe in another project. Now, one of the dialogs opened by the the MFC Doc/View was in the resource DLL and in order to establish a link between these two, the following task was done:

there was a extern "C" function which was created in a separate C++ within the MFC Doc/View project. Inside of the function, there was a call made to certain method in certain class within this project. Also, in the header file for that class, this function was defined as extern "C".

Next, an event handler in the resource DLL was built and it would make a reference to this extern "C" function.

Re: extern "C"

Paul M Watt21-May-02 5:30

Paul M Watt

21-May-02 5:30

Is your question what is extern "C" for?

All that extern "C" does, is instructs the compiler to not include namemangling in the symbols that it creates for that function, variable or whatever. This will allow dlls from other languages to more easily access the functions.

Normally the compiler adds decorations to the names in order to allow function overloading in C++. IF you trun off name mangling, then you will not be able to over load your functions. That is the drawback.

Good Luck

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

how using PTSTR type?

a_hic21-May-02 4:55

a_hic

21-May-02 4:55

hi,
look at this:
"ULONG PacketGetAdapterNames(PTSTR pStr, PULONG BufferSize)
Usually, this is the first function that should be used to communicate with the driver. It returns the names of the adapters installed on the system in the user allocated buffer pStr. After the names of the adapters, pStr contains a string that describes each of them."
suppose that in my machine I'he several adapters, hwo I use pStr to get those names?

James R. Twine21-May-02 5:16

James R. Twine

21-May-02 5:16

My guess would be:

<br />
    TCHAR caBuffer[ 4096 + 1 ];<br />
    DWORD dwBufSize = 4096;<br />
<br />
    PacketGetAdapterNames( caBuffer, &dwBufSize );<br />
    caBuffer[ 4096 ] = _T( '\0' );<br />
    //<br />
    // Read The Buffer Now...<br />
    //<br />

Peace!

-=- James.
"Fat people are hard to kidnap."
(Try Check Favorites Sometime!)

DialUp/LAN Question (Beginner ?)

21-May-02 4:45

1. How to programatically (VC++) find out the network default settings on a machine, if it's DialUp or LAN
2. How to find out if the connection is "ON", i.e the computer is connected ? That is either the DIalUp is on, or the LAN is active???

many thanks..
Hawk

Frown | :(

Joaquín M López Muñoz21-May-02 4:53

Joaquín M López Muñoz

21-May-02 4:53

1. Lee Hamel's article Retrieving NIC information using SNMP queries gives you the means to retrieve the list of IP interfaces installed on the machine. Please note interfaces can coexist both for LAN and Dial-up.

2. For LAN interfaces, there's no easy way to know if the machine is actually connected (meaning by that that the cable is plugged in.) There's a way to do it in Win2000, but the thing is messy. As for Dial-up interfaces, simply check whether the IP address is valid: when not connected, it is 0.0.0.0.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

21-May-02 5:10

many thanks, I'll try it out... for the LAN I thought using this statement will suffice:
if (!AfxSocketInit())
{
// some code ...
}
since all I care is to check if this can pass if the LAN is "on"... but in case of a modem that was mysterious to me since I don't want to invoke a DialUp connection if the connection isn't already "on", by using the above statement...
and this is why I wanted to check out some explicit way to find out what is on and what isn't...
thanks a lot.
Hawk Big Grin | :-D

Martin Ziacek21-May-02 5:17

Martin Ziacek

21-May-02 5:17

RasEnumConnections() could help to enumerate active connections. Rose | [Rose]

Nish Nishant21-May-02 4:59

Nish Nishant

21-May-02 4:59

the Cyber Hawk wrote:
How to find out if the connection is "ON", i.e the computer is connected ? That is either the DIalUp is on, or the LAN is active???

Try InetIsOffline(...)

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

21-May-02 14:07

Nish - Native CPian wrote:
Try InetIsOffline(...)

Ah great, I have to test that.
Some older articles suggested to resolve localhost (name->IP), then check if it's different to the loopback (127.0.0.1). InetIsOffline() looks more elegant. Smile | :)

21-May-02 23:33

I did inlclude <intshcut.h>, compiled OK but couldn't link with the following error "error LNK2001: unresolved external symbol __imp__InetIsOffline@4" ...

those are my includes:
#include <afxwin.h>
#include <afxext.h> // MFC extensions
#include <afxtempl.h> // MFC template classes
#include <afxsock.h> // MFC Sockets
#include <afxdisp.h> // Required by afxpriv.h
#include <afxpriv.h> // to get access to the T2A macro

#include <intshcut.h>

I would like to #include instead of #import; damn linker errors...I'll try to fix it myself, but if you have any thought why it won't link I'd appretiate it... regards..
H. Cry | :((

Nish Nishant21-May-02 23:46

Nish Nishant

21-May-02 23:46

You must add url.lib to the list of link modules Smile | :)

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.