Re: Database question ! - C / C++ / MFC Discussion Boards

Matthew Bache13-Sep-06 1:23

13-Sep-06 1:23

Naive programmer question time...
I'm reviewing some old code (not mine) for my employer and have found that some member functions are being called statically. Is this good practice? Is there any benefit to calling member functions statically? Example code structure as below.

<br />
class MyClass {<br />
 //...<br />
public:<br />
 void fn2() {//...}<br />
 void fn1() {MyClass::fn2();} // why not just fn2() ?<br />
};<br />

Is there a reason/benefit why fn2() gets called statically? Both fn1 and fn2 alter the calling object. Neither fn affects any static class data. MyClass is not invloved in any inheritance.

Matt

Re: C++ calling member functions statically

Steve S13-Sep-06 1:34

Steve S

13-Sep-06 1:34

It isn't a static member function, so it isn't being called statically.
Instead, it is being called explicitly. If it were a virtual function, then you would be guaranteeing to call the given class implementation (or the one it inherits, but there isn't any inheritance in this case.

There's no real advantage/disadvantage in this case, except that the compiler is being explicity told to use MyClass::fn2() rather than this->fn2().

Steve S
Developer for hire

Re: C++ calling member functions statically

Matthew Bache13-Sep-06 2:15

Matthew Bache

13-Sep-06 2:15

Thanks for the explanation.

Matt

Database question !

Bravoone_200613-Sep-06 1:00

Bravoone_2006

13-Sep-06 1:00

How can i set more then 25 rows in -> dwNewRowsetSize = 25;
---- fetching records in bulk------
pMyDatabase->SetRowsetSize(25);
Smile | :)

Bravoone

Re: Database question !

Hamid_RT13-Sep-06 1:28

Hamid_RT

13-Sep-06 1:28

Do you have any idea?

WhiteSky

Re: Database question !

toxcct13-Sep-06 1:47

toxcct

13-Sep-06 1:47

maybe... who knows Roll eyes | :rolleyes:

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: Database question !

Hamid_RT13-Sep-06 2:19

Hamid_RT

13-Sep-06 2:19

Its a secret Smile | :)

WhiteSky

Re: Database question !

toxcct13-Sep-06 2:03

toxcct

13-Sep-06 2:03

Flaviu_2006 wrote:
How can i set more then 25 rows in -> dwNewRowsetSize = 25;

is this is of any help :

dwNewRowsetSize = 30;

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: Database question !

sujtha13-Sep-06 2:19

sujtha

13-Sep-06 2:19

CDatabase db;
db.Open("MyDataSource", FALSE, FALSE, "ODBC;", FALSE);
CRecordset rs( &db );
rs.Open(...);

then call rs.SetRowSetSize(30);

if the recordset is not opened, then you are unable to set the more than 25 rows.

DataGrid Change size of colum

NorGUI13-Sep-06 0:59

NorGUI

13-Sep-06 0:59

Hello,

I am working with CDataGrid and I can not found how to change size of each colunm ! From resource I can change the size but it will be aplicated on all colunm but I need that each colunm have a other size!

Thank you to give me some tip !

AutreChien

Re: DataGrid Change size of colum

sujtha13-Sep-06 2:11

sujtha

13-Sep-06 2:11

Datagrid control, Subclass the datagrid header control. In that subclass, the header structure having column width properties. Here you can change for each and every column width.

Re: DataGrid Change size of colum

NorGUI13-Sep-06 8:24

NorGUI

13-Sep-06 8:24

I have check the header and the only fonction that I have founded is :

void put_DefColWidth(float newValue)
{
static BYTE parms[] = VTS_R4 ;
InvokeHelper(0x10, DISPATCH_PROPERTYPUT, VT_EMPTY, NULL, parms, newValue);
}

but there no other fonction to change each colunm !

header files name is DataGrid1.h !

AutreChien

edit control

kumar_mk13-Sep-06 0:44

kumar_mk

13-Sep-06 0:44

Hi, this is a low priority bug of my application, i have an Edit control (READ-ONLY property is TRUE, TABSTOP property is FALSE) which is used to display some Message. The problem is that the "Message" of the edit control is getting selected when i am pressing the UP arrow key from the OK and CANCEL buttons of the dialog box, the "Message" should not get selected, how??

one thing i have written this code in OnInitDialog() to show the message in BOLD/BIGGER font

CFont myFont;
myFont.CreatePointFont(120, _T("Arial"), NULL);
CEdit* pBoxOne;
pBoxOne = (CEdit*)GetDlgItem(IDC_STATUS_EDIT);
pBoxOne->SetFont(&myFont, TRUE);

i have tried checking and unchecking all the styles, extented styles in edit properties, but of no use, may be this problem is arising because of the code i have written for the FONT, do i need to add anything extra in the code?? Pls Help!!!

thanx in advance
kumar

Re: edit control

Nishad S13-Sep-06 0:53

Nishad S

13-Sep-06 0:53

kumar_windows wrote:
may be this problem is arising because of the code i have written for the FONT

Why didn't you try to comment out this code and try? Wink | ;)

Actually what you got is the basic behaviour.
I would like to handle this problem in PreTranslateMessage of the dialog... Smile | :)

- NS -

Re: edit control

Akt_4_U13-Sep-06 1:41

Akt_4_U

13-Sep-06 1:41

Pls make the "Disabled" property of Edit control TRUE. Then it will not get selected.

Praveen

Akkott

Re: edit control

kumar_mk13-Sep-06 2:12

kumar_mk

13-Sep-06 2:12

thank you very much Smile | :)

thanx in advance
kumar_windows

CMenu - Menu appears as a narrow bar

kk_vp13-Sep-06 0:33

kk_vp

13-Sep-06 0:33

Hi,

I have the below code in my app for showing a menu on right click on a systray icon.

CMenu SystrayMenu;
CPoint pt;
GetCursorPos(&pt);
SystrayMenu.CreatePopupMenu();
SystrayMenu.LoadMenuW(IDR_MENUSYSTRAY);
SystrayMenu.TrackPopupMenu(TPM_BOTTOMALIGN|TPM_LEFTBUTTON,pt.x,pt.y,this,0);

The menu appears on right click, but I only get a narrow bar.
In the menu resource I have one item "Exit", but nothing is shown.

What could be the problem ? Frown | :(

- KK

Re: CMenu - Menu appears as a narrow bar

Naveen13-Sep-06 0:49

Naveen

13-Sep-06 0:49

there is small problem in ur code. Modify it as below

CMenu SystrayMenu;
CPoint pt;
GetCursorPos(&pt);
SystrayMenu.CreatePopupMenu();
SystrayMenu.LoadMenuW(IDR_MENUSYSTRAY);
SystrayMenu.GetSubMenu(0)->TrackPopupMenu(TPM_BOTTOMALIGN|TPM_LEFTBUTTON,pt.x,pt.y,this,0);

nave

Re: CMenu - Menu appears as a narrow bar

kk_vp13-Sep-06 1:06

kk_vp

13-Sep-06 1:06

I get an access violation error when I do that.

- KK

Re: CMenu - Menu appears as a narrow bar

Naveen13-Sep-06 1:15

Naveen

13-Sep-06 1:15

plz ensure that the menu have submenus.

make a menuu of below structure( similar to a file menu in notepad ) and try
File
Open
Close

nave

Re: CMenu - Menu appears as a narrow bar

kk_vp13-Sep-06 1:21

kk_vp

13-Sep-06 1:21

I got it working. Thank you.

What I wanted is just one "EXIT" to be present in the right click menu.
So I just had EXIT in top most menu.
Then I added another item Exit in it's submenu and it works, shows only the submenu.
thanks again.

- KK

Save an file with FILE_ATTRIBUTE_READONLY Attribute

bosfan13-Sep-06 0:17

bosfan

13-Sep-06 0:17

Hello comunity,
when i create an new file(CStdioFile) and write something in them i close it with CStdioFile::Close();,
but how to set the attribute FILE_ATTRIBUTE_READONLY to avoid that someone make changes at random,
my program need this file after create to work with them, and when is inside the file something
wrong my program want crash!

regards
break;

Re: Save an file with FILE_ATTRIBUTE_READONLY Attribute

Mohammad A Gdeisat13-Sep-06 0:26

Mohammad A Gdeisat

13-Sep-06 0:26

If I understood u right, you dont want another process to access the file when ur program is using it, to do this use CFile::shareExclusive with the Open operation.

if u open a file while in read-only, u cant write in it unless u clear this attribute, so that ur program crashes.

Mohammad

And ever has it been that love knows not its own depth until the hour of separation

Re: Save an file with FILE_ATTRIBUTE_READONLY Attribute

Garth J Lancaster13-Sep-06 0:34

Garth J Lancaster

13-Sep-06 0:34

Im not sure I understand all you're saying but :-

assuming : - LPCTSTR lpFileName

DWORD dwFileAttributes = GetFileAttributes( lpFileName);
long mask = dwFileAttributes;
if( ! ( dwFileAttributes & FILE_ATTRIBUTE_READONLY))
{
mask = dwFileAttributes | FILE_ATTRIBUTE_READONLY;
if( ! SetFileAttributes( lpFileName, mask))
{
// Flag the error here
return;
}
}

is probably what you're looking for - your program would of course have to remove the readonly flag before it used the file - the suggestion above this is also valid (ie exclusive flag)

'g'

Re: Save an file with FILE_ATTRIBUTE_READONLY Attribute

bosfan13-Sep-06 4:20

bosfan

13-Sep-06 4:20

Hello Garth,
yes, this is that what im looking for!
but need some help again!
Please check this code:

<br />
// <br />
// first i check if is ReadOnly File!<br />
DWORD dwFileAttributes;<br />
DWORD mask;<br />
<br />
dwFileAttributes = GetFileAttributes(csFileName); // dwFileAttributes have now 0x00000021, ok, is archive and readonly protected<br />
mask = dwFileAttributes;<br />
<br />
if((dwFileAttributes & FILE_ATTRIBUTE_READONLY))<br />
{<br />
mask = dwFileAttributes & FILE_ATTRIBUTE_NORMAL; // mask have now 0x00000000, why not 0x00000020->archive! Ok, not nice but this let me to open my file!<br />
if(!SetFileAttribute(csFileName, mask))<br />
{<br />
	AfxMessage(csErrorMessage);<br />
}<br />
}<br />
<br />
// to open file with mask == 0x00000000 make no problems<br />
cMyFile.Open(...);<br />
// write some data to file<br />
// close file<br />
// now set the flag ReadOnly:<br />
dwFileAttributes = GetFileAttributes(csFileName); // here returns a value 0x00000020 // ok, is an archive!<br />
mask = dwFileAttributes;<br />
if(!(dwFileAttributes & FILE_ATTRIBUTE_READONLY))<br />
{<br />
mask = dwFileAttributes | FILE_ATTRIBUTE_READONLY; // mask have now 0x00000021 // archive and readonly protected<br />
if(!SetFileAttributes(csFileName, mask))<br />
{<br />
// errorhandling<br />
}<br />
}<br />

This is what im doing with your response!
Is this right, take a look to my sample please!
Maybe is not the best way, but they do wat i want! Confused | :confused:

with best regards
break;

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