C++ pointer question - C / C++ / MFC Discussion Boards

Re: Turn of Ellipsis in ListView

Prakash Nadar16-Mar-04 15:06

Prakash Nadar

16-Mar-04 15:06

What is the meaning of turn of ellipse?

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Re: Turn of Ellipsis in ListView

Anonymous16-Mar-04 15:19

Anonymous

16-Mar-04 15:19

By Ellipsis I mean three dots (...)

Re: Turn of Ellipsis in ListView

Steve S16-Mar-04 23:58

Steve S

16-Mar-04 23:58

I assume you mean 'turn off' rather than 'turn of', since that makes no sense.
This is happening because with no manifest the control is drawing slightly differently, and has more client space. The easiest solution would be to make the control slightly bigger, and/or increase the column width.

Steve S

Re: Turn of Ellipsis in ListView

Rightoguy17-Mar-04 4:38

Rightoguy

17-Mar-04 4:38

Yeah...sorry for the typo. I tried increasing the column width but still no avail.
No matter how big the Columnwidth still I couldn't remove the ellipsis.
I even tried wrapping the text in two lines after calculating the number of characters that will fit in the specified columnwidth by calling the function: GetTextExtentExPoint
Then I tried using the SetWindowTheme function which is sitting in uxtheme.dll
I still have the same result.
Any help

public member not working

BlackDice16-Mar-04 10:22

BlackDice

16-Mar-04 10:22

my classview info won't show up anymore and everytime I try to compile my program I get an error telling me that I can't access a protected member variable (value). but it's declared like this:

public:
char *value;
void release();

it was protected at once, but now it's not and I've rebuilt all a number of times and nothing seems to work. can anyone help?

If it's broken, I probably did it

bdiamond

Re: public member not working

David Crow16-Mar-04 10:45

David Crow

16-Mar-04 10:45

Can you trim the class, including the member-variable access, down to just a few lines that exhibits the problem?

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: public member not working

BlackDice16-Mar-04 10:50

BlackDice

16-Mar-04 10:50

thanks, I got it working. I was trying to cheat and mess with a class that I didn't write and change the access to public, but I found a right way to do it, so I don't have to worry about it. Thank you anyway!

If it's broken, I probably did it

bdiamond

C++ pointer question

patnsnaudy16-Mar-04 10:20

patnsnaudy

16-Mar-04 10:20

If I have a pointer to an object foo is there anyway to tell if that object actually exists?

Say I only want one window open at a time.

void
foo::openWindow()
{
   static foo* ptr = NULL;
   if (ptr)  
      ptr->closeWindow();
   ptr = this;

   // open this window 
   ...
}

So, the second time through this code I want to know if ptr is still valid, because it may have been deleted without my knowledge.

I know there are other ways to do this, but I want to know if I can figure out if ptr still exists.

I've tried adding a ptr = dynamic_cast<foo*>(ptr);, but this throws an exception if ptr has been deleted, and I'd rather not use a try block.

Thanks in advance

Re: C++ pointer question

Joe Woodbury16-Mar-04 10:55

Joe Woodbury

16-Mar-04 10:55

I completely fail to see the purpose of your code, but that aside, you can simply check whether the 'this' pointer is NULL.

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

Re: C++ pointer question

patnsnaudy16-Mar-04 11:11

patnsnaudy

16-Mar-04 11:11

Yeah but if you create

foo *a = new foo();
foo *b = new foo();

a.openWindow();
b.openWindow(); // This should close a.
delete b;       // ptr in openWindow() still points 
                //  to the space b used to occupy.
a.openWindow(); // Trys to close b, but b no longer exists (ERROR).

I know I could create a member and set it to this in openWindow and NULL in closeWindow, but I do not want to have a member for this.

If you change the code to use a dynamic_cast and put a try-catch(...) around it this will work as is, but the powers that be don't like try-catch, so I'm not allowed to use it.

Re: C++ pointer question

Christian Graus16-Mar-04 11:29

Christian Graus

16-Mar-04 11:29

patnsnaudy wrote:
but the powers that be don't like try-catch, so I'm not allowed to use it.

Not being allowed to use try..catch is wrong, but so is a design that throws exceptions based on bad coding, so on aggregate, I'm with the 'powers that be'.

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

Re: C++ pointer question

Ravi Bhavnani16-Mar-04 17:35

Ravi Bhavnani

16-Mar-04 17:35

It's good coding hygiene to set a deleted pointer to NULL. This will help prevent run-time errors and could make your code simpler.

/ravi

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Re: C++ pointer question

TFrancis16-Mar-04 10:58

TFrancis

16-Mar-04 10:58

If there's some function call out there that tells you if a spot in memory is valid that'd be a real easy way of doing this. But I don't know of one.

My suggestion. Make ptr a static member of the foo class. Then, in your foo destructor, if ptr == this, set ptr = NULL.

Tim

Re: C++ pointer question

patnsnaudy16-Mar-04 11:02

patnsnaudy

16-Mar-04 11:02

I know I can do this, but I did not want to add a member for this.

Thanks though!

Jerry

Re: C++ pointer question

David Crow17-Mar-04 3:03

David Crow

17-Mar-04 3:03

TFrancis wrote:
If there's some function call out there that tells you if a spot in memory is valid that'd be a real easy way of doing this. But I don't know of one.

How about:

IsBadReadPtr()
IsBadCodePtr()
IsBadStringPtr()
IsBadWritePtr()

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: C++ pointer question

Christian Graus16-Mar-04 11:31

Christian Graus

16-Mar-04 11:31

Add an operator HWND to the class that returns the window handle and call ::IsWindow.

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

Re: C++ pointer question

patnsnaudy16-Mar-04 12:55

patnsnaudy

16-Mar-04 12:55

There is already a function to return HWND I think, if this is derived from the window class (I'll have to check tomorrow at work). ::IsWindow is a great suggestion! I was looking for a magical function that would look at a piece of memory and tell me if it had been deleted, but IsWindow should work.

Thanks

Re: C++ pointer question

Prakash Nadar16-Mar-04 14:55

Prakash Nadar

16-Mar-04 14:55

it will not work if the pointer to the dialog is deleteed.

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Re: C++ pointer question

patnsnaudy17-Mar-04 3:56

patnsnaudy

17-Mar-04 3:56

By it will not work does that mean that it will crash if the pointer has been deleted?

Re: C++ pointer question

Prakash Nadar17-Mar-04 16:45

Prakash Nadar

17-Mar-04 16:45

yes,it will very unpredictable, it may crash in some cases and it will work in some cases. but then working with deleted pointer is very bad idea.

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Re: C++ pointer question

Ryan Binns16-Mar-04 17:10

Ryan Binns

16-Mar-04 17:10

To determine if a pointer points to readable memory, use the IsBadReadPtr() function. If it returns FALSE, then the pointer cannot be read.

Hope this helps,

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

I gave in (sln)

patnsnaudy18-Mar-04 2:12

patnsnaudy

18-Mar-04 2:12

I just created a static pointer to the window and set it to this in the openWindow function and NULL in the dtor.

Thanks

How to TURN UNICODE ON.

HAHAHA_NEXT16-Mar-04 10:19

HAHAHA_NEXT

16-Mar-04 10:19

Hi all.

Using TCHAR is fine, but i wanted to know if there would be a way of turning UNICODE on for my application (#define _UNICODE does nothing). Needed for testing (I fear LOTS of errors Dead | X|

).

Please help.

Re: How to TURN UNICODE ON.

David Crow16-Mar-04 10:34

David Crow

16-Mar-04 10:34

Have you also defined UNICODE (in addition to _UNICODE)? Make sure they are both defined as close to the top of stdafx.h as possible.

With both defined, TCHAR will resolve to unsigned short. Otherwise it will resolve to char.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: How to TURN UNICODE ON.

HAHAHA_NEXT16-Mar-04 10:39

HAHAHA_NEXT

16-Mar-04 10:39

Txs. This was fast.

Now how do i get i get sprintf working.
(i do not want to use swprintf because it is unicode only)

For printf there is at least _tprintf , but i can find anything for
sprintf. Is there an euivelent and if not how can i redirect the ourput
to a TCHAR variable.

Thx in advance.

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