Why the Size of an Empty Class is 1 ?? - C / C++ / MFC Discussion Boards

zahid_ash19-May-06 2:12

19-May-06 2:12

OK,

copying a file while it is open means A "AA.doc" file is open in MS Word . and at the same time my application wants to copy it on another location.

would the simple read and write to other location works. i thought that may be the document is locked.

Regards.

Re: make a copy of file while its open

Laxman Auti19-May-06 2:48

Laxman Auti

19-May-06 2:48

zahid_ash wrote:
would the simple read and write to other location works. i thought that may be the document is locked.

I have tried the demo, but the MS Word not allows this operation .
i think it opens the file in Exclusive read/write mode so that no one can access the file.

may have to set the some permissions Unsure | :~

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You can if you think you can
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Re: make a copy of file while its open

_AnsHUMAN_ 19-May-06 2:41

_AnsHUMAN_

19-May-06 2:41

You can open the file in the read/write or the append mode.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: make a copy of file while its open

Maximilien19-May-06 2:46

Maximilien

19-May-06 2:46

I think you can use ::SHFileOperation to copy openned files.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: make a copy of file while its open

zahid_ash19-May-06 3:07

zahid_ash

19-May-06 3:07

would there be a difference between simple read and write . and using ::SHFileOperation()

Regards.

Re: make a copy of file while its open

Sam Hobbs19-May-06 3:38

Sam Hobbs

19-May-06 3:38

Notice that you said "my app" but you said nothing about Word. It would help others to help you to mention details such as the fact that the data is a Word file. You would get better answers that way.

I would use the Word objects to copy the data. That is, the objects used by VBA. I am not sure that will work but I would be very, very surprised if it is not possible.

Re: make a copy of file while its open

knoxplusplus23-May-06 7:34

knoxplusplus

23-May-06 7:34

Hi !!!

If you use the functions of the WIN32API for the copying the files, ... you don't have to close the opened file, it does it self.

By !!!

-:KNOX:-

Why the Size of an Empty Class is 1 ??

NiceNaidu19-May-06 2:01

NiceNaidu

19-May-06 2:01

Hi Guys,

This is a question asked by one of my junior.
Though i could able 2 answer him,by telling him to ensure different memory location for each instance of the class,the size is set as 1.

But I am(ofcourse he tooo) not convinced with my answer.

Can anyone of u give me a good explanation for this Question??

Appu..
"If you judge people, you have no time to love them."

Re: Why the Size of an Empty Class is 1 ??

Laxman Auti19-May-06 2:07

Laxman Auti

19-May-06 2:07

When you create the object of the class then the for the existence of the object there should be atleast memory so it is is 1 byte even the class dont having single variable

and if the class contains atleast one virtual function then size is 2 bytes

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You can if you think you can
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Re: Why the Size of an Empty Class is 1 ??

NiceNaidu19-May-06 2:14

NiceNaidu

19-May-06 2:14

A_Laxmanif the class contains atleast one virtual function then size is 2 bytes

r u sure about it ??

If it contains a virtual function ,then its size should be either 4(since the memory location will be 4 bytes long) or 5(4+1) bytes ..How can it be 2 bytes.

I am confused.

Appu..
"If you judge people, you have no time to love them."

Re: Why the Size of an Empty Class is 1 ??

Laxman Auti19-May-06 2:22

Laxman Auti

19-May-06 2:22

NiceNaidu wrote:
I am confused.

don't be confused.

In case of 16 bit applications(DOS)
the size of class when virtual function present is 2 bytes

In case of 32 bit application(Windows)
the size of class when virtual function present is 4 bytes

In case of empty class for both cases it is 1 byte

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-- modified at 8:24 Friday 19th May, 2006

Re: Why the Size of an Empty Class is 1 ??

David Crow19-May-06 3:07

David Crow

19-May-06 3:07

NiceNaidu wrote:
...to ensure different memory location for each instance of the class...

This is the answer. What else are you looking for? Confused | :confused:

FAQ[^]

"The largest fire starts but with the smallest spark." - David Crow

Extracting the user input from Edit Box

VinayCool19-May-06 2:00

VinayCool

19-May-06 2:00

Hi,

I have a dialog window in which user has to enter some text in the IDC_WORD after clicking on search button i want the value to be stored in a variable line,

I have created a variable m_WORD of CString type ,

CString line;
line = m_WORD;
char * w =(char *) (LPCTSTR) line;
word = w;

but the value is not getting stored in line I used F5 and checked value of m_WORD is empty "" what will be cause ..?? can anyone help me with this….

Regards,
Vinay Charan.

Re: Extracting the user input from Edit Box

NiceNaidu19-May-06 2:08

NiceNaidu

19-May-06 2:08

Use UpdateData(TRUE) before line = m_WORD

Appu..
"If you judge people, you have no time to love them."

Re: Extracting the user input from Edit Box

Laxman Auti19-May-06 2:35

Laxman Auti

19-May-06 2:35

vinaycool wrote:
CString line;
line = m_WORD;
char * w =(char *) (LPCTSTR) line;

char * str=new char[MAX];
UpdateData();
lstrcpy(str,m_test.GetBuffer(m_test.GetLength()));

The code copies the data from the edit box into the str variable.

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You can if you think you can
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Re: Extracting the user input from Edit Box

ThatsAlok19-May-06 2:45

ThatsAlok

19-May-06 2:45

A_Laxman wrote:
vinaycool wrote: CString line;line = m_WORD;char * w =(char *) (LPCTSTR) line;

nope this code will also work well, have a try!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Re: Extracting the user input from Edit Box

Laxman Auti19-May-06 2:51

Laxman Auti

19-May-06 2:51

ThatsAlok wrote:
nope this code will also work well, have a try!

Yes buddy,
I have tried the code and works fine.
as well tried another to do same and posted in my previous post.;P

Knock out 't' from can't,
You can if you think you can
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Re: Extracting the user input from Edit Box

ThatsAlok19-May-06 2:41

ThatsAlok

19-May-06 2:41

vinaycool wrote:
I have created a variable m_WORD of CString type ,

Have you called GetWindowText in that Function or UpdateData(FALSE) !

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Re: Extracting the user input from Edit Box

David Crow19-May-06 3:09

David Crow

19-May-06 3:09

Use:

GetDlgItem(IDC_WORD)->GetWindowText(m_WORD);

"The largest fire starts but with the smallest spark." - David Crow

Re: Extracting the user input from Edit Box

Hamid_RT19-May-06 19:10

Hamid_RT

19-May-06 19:10

use UpDateData then

m_youret.GetWindowText( m_WORD);

whitesky

Re: Extracting the user input from Edit Box

rbid19-May-06 21:08

rbid

19-May-06 21:08

There is another way to do it Smile | :)

Assign a "Control" variable to your edit box (CEdit m_textEdit).
Use the method GetWindowText() for retrieving the results

void CDemo::OnBnClickedSearchButton()
{
    ...
    CString userResponseText;
    m_textEdit.GetWindowText(userResponseText);

    // userResponseText now contains user response..
    ...
}

Here you don't need to worry about UpdateData that usually has side effects.

Just wanted to give you another way to do it.

-- Ricky Marek (AKA: rbid)
-- "Things are only impossible until they are not" --- Jean-Luc Picard

My articles

.ncb and .pch file

big_denny_20019-May-06 1:54

big_denny_200

19-May-06 1:54

Hi all

I have a project, created in VS2005.

When I enter its directory, inside I have 2 files and 3 folders : Debug, MyProject, Release, MyProject.ncb, MyProject.sln

Strange is that MyProject.ncb is 16 MB in size.
And other files(folders), together are only 4 MB(If I clear the debug and release folders).

Strange is also that MyProject.pch file is 12MB, when Debug folders of my project is not empty.

Why are these files so large ?

Size of total source files I use is only 3MB.

Thank you.

Re: .ncb and .pch file

Sebastian Schneider19-May-06 2:08

Sebastian Schneider

19-May-06 2:08

NCB is the Intellisense Database. This sometimes messes up BADLY. I have had a NCB-File with a size of 1.2 GB (!!!). Sometimes the Parser will get a hick-up and go crazy. Just delete the file, it's automatically recreated when you reload your project. Looking stuff up (code completion etc.) might be a bit slow, but will soon get back to its old self.

The PCH-File is the precompiled header file. You can delete that one as well, it also will be recreated. If it is not there, compiling might take a bit longer (because it has to be recreated).

If you do not need recompiled headers, turn them off in the project properties.

Cheers,
Sebastian

--
Contra vim mortem non est medicamen in hortem.

Use Strlog in the application

vemula_vijay19-May-06 1:53

vemula_vijay

19-May-06 1:53

Hello everyone,

i am working in c++.
is it possible to use strlog.h in win32 console application.
if so where can i find the file and the documentation for using it.

thanks in advance,

regs
vijay

Re: Use Strlog in the application

Laxman Auti19-May-06 2:02

Laxman Auti

19-May-06 2:02

vemula_vijay wrote:
where can i find the file

In vs6.0 the file is not found and
you can get the file from the following links
http://www.koders.com/c/fid08988FEB1599197A286D0BB669376700B6051560.aspx[^]
http://www.koders.com/cpp/fid604EACFF7220C14074F04C2E10B75B5C3CBA5B96.aspx[^]

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