Re: I want to copy strings,but occur this....."Access to memory errors....",why? [modified] - C / C++ / MFC Discussion Boards

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 22:40

Richard MacCutchan

11-Oct-09 22:40

theCPkid wrote:
Any idea what's the problem in the following code?

Apart from the fact that it will print "Yello", nothing.

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

theCPkid11-Oct-09 22:59

theCPkid

11-Oct-09 22:59

have you really tried it? i have the feeling that you will get write access error...

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 23:40

Richard MacCutchan

11-Oct-09 23:40

theCPkid wrote:
i have the feeling that you will get write access error...

Yes, you're right; my apologies.

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

carter200011-Oct-09 18:31

carter2000

11-Oct-09 18:31

Loveprogramer wrote:
char *from = "c plus plus";
char *to = "oooooooooooooooo";

Here "from" and "to" are constant strings exactly, so the codes below would be mistake.
"*to++ = *from++".
If you declare "from" and "to" as array of string, your program would work fine.
Just like:
char from[] = "c plus cplus";
char to[] = "oooooooooooooooooooooo";

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 22:42

Richard MacCutchan

11-Oct-09 22:42

carter2000 wrote:
Here "from" and "to" are constant strings exactly, so the codes below would be mistake.

Not true; declaring a string as char* str or char str[] yields the same result.

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

carter200011-Oct-09 23:09

carter2000

11-Oct-09 23:09

Maybe I made something wrong, but it just works fine in my computer. My compiler is VS2008.

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 23:45

Richard MacCutchan

11-Oct-09 23:45

foot - mouth - brain!

I must remember brain comes first. Sigh | :sigh:

Re: I want to copy strings,but occur this....."Access to memory errors....",why? [modified]

Richard MacCutchan11-Oct-09 22:39

Richard MacCutchan

11-Oct-09 22:39

I think the problem is probably in the following statement: while((*to++ = *from++) != '\0');. The C++ language specification for the assignment operator states "The assignment operators return the value of the object specified by the left operand after the assignment." i.e the to pointer. Thus in the above statement the comparison is done with the next element of the to array, which being longer than the from array, contains the character 'o'. The while loop is now out of control as it is copying garbage. Rework your loop so that it tests the source array element for '\0', rather than the destination.

[EDIT]Sorry, I got this wrong, the result of the expression is to before it gets incremented, hence it is correct.[/EDIT]

modified on Monday, October 12, 2009 5:45 AM

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Iain Clarke, Warrior Programmer11-Oct-09 23:27

Iain Clarke, Warrior Programmer

11-Oct-09 23:27

Well, what have you discovered for yourself?

Does that copy_pointer loop die on the first time it does something?
When it hits a NULL?

Does it die if to is a dynamically created variable?

ie,

char *buf = new char [128];  // or (char*)malloc(128); if you prefer
copy_pointer (from, buf);
delete [] buf;               // or free (buf); if you prefer.

I'm 90% sure I know what's wrong, but I'll wait for you to run these tests and see if you can find out for yourself.

Iain.

I have now moved to Sweden for love (awwww).
If you're in Scandinavia and want an MVP on the payroll (or happy with a remote worker), or need contract work done, give me a job! http://cv.imcsoft.co.uk/[^]

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

rejupal12-Oct-09 20:10

rejupal

12-Oct-09 20:10

Try this

char from[] = "c plus plus";
char to[] = "oooooooooooooooo";

instead of

char *from = "c plus plus";
char *to = "oooooooooooooooo";

IPropertyUI::ParsePropertyName return always E_FAIL

Emulator ®11-Oct-09 16:02

Emulator ®

11-Oct-09 16:02

Hi all!

Why this Function (http://msdn.microsoft.com/it-it/library/dd758083%28en-us,VS.85%29.aspx) return always E_FAIL?

Example of use:
ULONG eat = 4;
pUI->ParsePropertyName(_T("Size"), &fmtid, &pid, &eat);

Return E_FAIL when have to return the FMTID/PID correspondent of Property...

Please Help! Frown | :(

Re: IPropertyUI::ParsePropertyName return always E_FAIL

«_Superman_»11-Oct-09 16:06

«_Superman_»

11-Oct-09 16:06

What is the HRESULT value that is returned?
The return value will probably give you a better idea about what is wrong.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Re: IPropertyUI::ParsePropertyName return always E_FAIL

Emulator ®11-Oct-09 16:10

Emulator ®

11-Oct-09 16:10

HRESULT is 0x80004005

I have printed returned HRESULT in Hexadecimal...

Re: IPropertyUI::ParsePropertyName return always E_FAIL

Emulator ®11-Oct-09 16:23

Emulator ®

11-Oct-09 16:23

I have resolved the problem Smile | :)

the ULONG parameter must be 0... thanks anyway Smile | :)

Re: IPropertyUI::ParsePropertyName return always E_FAIL

Emulator ®11-Oct-09 23:17

Emulator ®

11-Oct-09 23:17

But on Windows Vista don't work!

Grrrrrrrrrrrrr

OnPaint Notification question

ForNow11-Oct-09 14:52

ForNow

11-Oct-09 14:52

Hi,

I have a CFramewnd from which I create CDialog modeless flavor..

In the CDialog one of the controls is a CRicheditctrl which I populate with data

My problem the data from the Cricheditctrl is never displayed

The Dialog remains Solid Gray which is the same Background Color as the CFrameWnd Background

It just occurred to me the when I get OnPaint Notfication for the CFrameWnd I probably paint the Cdialog

Which lies at the Upper Left hand corner of the CFameWnd

However When I hit a breakpoint on the CDialog::Create I also set a BreakPoint on the OnPaint notfication handler

it never gets executed

When I change the Background color of the CFrameWnd to Red the CDialog displayes as Red Too...

Any Ideas ???

thankx

Re: OnPaint Notification question

«_Superman_»11-Oct-09 15:35

«_Superman_»

11-Oct-09 15:35

Check to see if you have called the AfxInitRichEdit[^] function before displaying the dialog.
If not, call the function in the InitInstance override of your CWinApp derived class.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Re: OnPaint Notification question

ForNow11-Oct-09 16:02

ForNow

11-Oct-09 16:02

Have that

Funny thing I have a Modal dialog Box with 2 single line edit controls which displays properly

I am thinking of coding my own Create for the CFrameWnd with the "WS_CLIPCHILDREN" style

I am thinking this would go CFrameWnd contructer...

Localizing MFC standard strings

_Andrew11-Oct-09 11:32

_Andrew

11-Oct-09 11:32

Hi!

I've a problem localizing MFC error messages. Currently, I need to change AFX_IDP_PARSE_INT_RANGE which is used in DDV_MinMaxInt to display error message when int value is out of range.
I added the string to the string table of my application, but it doesn't seems to change the error message in MessageBox. Rebuilding doesn't help.

I've checked the code, an in MyProject.rc MFC wizard added:

STRINGTABLE
BEGIN
AFX_IDP_PARSE_INT_RANGE "Значение может быть от %s до %s"
END

And, as I said earlier, the MFC dialog is shown with english (default) version of this string.

Please help me with this problem,
I need to release the project tomorrow morning!

Thank you,
Andrey Yanov

Re: Localizing MFC standard strings

David Crow12-Oct-09 3:12

David Crow

12-Oct-09 3:12

_Andrew wrote:
Please help me with this problem,
I need to release the project tomorrow morning!

To borrow a quote, lack of planning on your part does not constitute an emergency on ours.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Finished drawing dialog

clint198211-Oct-09 9:52

clint1982

11-Oct-09 9:52

Hi I want to make a loading message box which disappears once the loading was finished.
In order to do that I decided to use the function DialogBox in order to create a modal dialog, however, I couldn't find a message that indicates that dialog has finished drawing itself.
I want to start the loading sequence right after the dialog and the message of "loading" appears on the dialog.

Any suggestions ?

I would like to use a dialog in order to easily make a nice loading message.

Thanks a lot,
Clint

Re: Finished drawing dialog

Emulator ®11-Oct-09 9:54

Emulator ®

11-Oct-09 9:54

In wich ambient you are doing this? MFC?

In that case you can take OnInitDialog event or.. WM_INITDIALOG

Re: Finished drawing dialog

clint198211-Oct-09 9:57

clint1982

11-Oct-09 9:57

I tried WM_INITDIALOG, but it happens before the dialog has finished drawing itself, so the message doesn't appear.

Re: Finished drawing dialog

Emulator ®11-Oct-09 10:06