C / C++ / MFC Discussion Boards

Re: CArray: SetSize()-->ConstructElements()

G. Steudtel21-Aug-03 0:27

21-Aug-03 0:27

Hi,
Well the problem is the constructor.
If you create an array of objects then the default constructor is called for each object in your array. If you have no default constructor, that is a constructor with no parameters or all parameters set to default values, the construction of the array will fail.
I think that's the reason why you need to implement ConstructElements to make sure the right constructor gets called.

Regards

G. Steudtel

Re: CArray: SetSize()-->ConstructElements()

7stud21-Aug-03 12:26

7stud

21-Aug-03 12:26

Hi,

Thanks for the response.

First, I'm confused about how allocating memory for a CArray works, and second I have no idea what I'm supposed to do to store objects with a dynamically allocated data member in a CArray.

1)My book says the default version of ConstructElements() allocates memory for the number of elements you want to store in the array, but it does not call a constructor for your objects. I assume that it must allocate memory using sizeof(<class name>) then. Now, how come a regular object can be stored in the CArray but you have to do something extra for an object with a dynamically allocated data member?

2) How do you implement ConstructElements() for the simple object with a dynamiclly allocated data member that I listed in my first post?

Need MMC expert

YaronNir20-Aug-03 22:08

YaronNir

20-Aug-03 22:08

Hi all,

I am using the MMC Snap in object.

i have a property sheet (the mmc property sheet). i've added 3 pages to it
and displayed it. now i need to disable tab 2 and 3......

in the call back method CreatePropertyPages(LPPROPERTYSHEETCALLBACK lpProvider,long handle, IUnknown* pUnk, DATA_OBJECT_TYPES type) - i am creating the pages using

hr = lpProvider->AddPage(....)

my question is how do i disable this page now??? the LPPROPERTYSHEETCALLBACK doesn't supply a method to do that...

can any1 help?

thanks in advanced

Yaron

Ask not what your application can do for you,
Ask what you can do for your application

set environment variables at IDE?

novachen20-Aug-03 20:40

novachen

20-Aug-03 20:40

My application should properly setup with several environment variables.
I must set these before i begin debugging so i debug in the dos command line now. How can i set the environment variables in the IDE of vc6 or vs7?
Any idea?

Re: set environment variables at IDE?

David Crow21-Aug-03 4:05

David Crow

21-Aug-03 4:05

Assuming you are using Windows 2000 (and probably XP), open the System applet in Control panel. Click on the Advanced tab. Click the Environment Variables button.

You can do the same thing with Windows 9x, but I'm not familiar enough with the UI to say.

Link for sending mails

hph20-Aug-03 20:34

hph

20-Aug-03 20:34

Hi,

i want to add a link to my MFC dialog, which shall popup outlooks window for sending mails. I know how i can popup this window, but i don't know how i can add a link into my dialog which looks like the same as real links (like them in a html-Site)

Re: Link for sending mails

Dominik Reichl20-Aug-03 20:50

Dominik Reichl

20-Aug-03 20:50

I use this control: http://www.codeproject.com/miscctrl/hyperlink.asp[^]

Big Grin | :-D

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Link for sending mails

hph20-Aug-03 20:58

hph

20-Aug-03 20:58

Thank you, dominik!

Greetings,
hph

Re: Link for sending mails

David Crow21-Aug-03 4:12

David Crow

21-Aug-03 4:12

ShellExecute(..., "mailto:", ...) would be one way.

Re: Link for sending mails

Jack_pt21-Aug-03 16:04

Jack_pt

21-Aug-03 16:04

You can do that if you derive your dialog from CDHtmlView.

How Do I Detect DAO Installed?

John Clump20-Aug-03 20:12

John Clump

20-Aug-03 20:12

Hi everyone. I need to detect whether or not DAO 3.5 or higher is installed on a system, specifically the Jet engine. Both my installer and the program itself will detect this. I looked over at codeguru and found an article which says to check to see if the key "HKEY_LOCAL_MACHINE\Software\Microsoft\Jet\3.5\Engines". I assume, logically, I would check to see if the Jet 3.5 subkey exists to check if the Jet 3.5 engine is installed.

My question is, is this the best way to do this, and is it the way Microsoft recommends? I searched MSDN for hours and couldn't find an article on the proper way to detect a DAO installation. And, will this work if the user has a higher version than 3.5 installed? Thanks!

Re: How Do I Detect DAO Installed?

Dominik Reichl20-Aug-03 21:06

Dominik Reichl

20-Aug-03 21:06

I have no idea what is the recommended way by Microsoft but I would enumerate all registry keys under HKEY_LOCAL_MACHINE\Software\Microsoft\Jet\ and parse the returned strings to version numbers...

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: How Do I Detect DAO Installed?

Joel Lucsy21-Aug-03 2:14

Joel Lucsy

21-Aug-03 2:14

We use a try-catch around AfxDaoInit() function to test if DAO is working correctly and abort/warn if it is not. It throws a CDaoException if something isn't right.

Joel Lucsy

File Access Time

wow999920-Aug-03 20:10

wow9999

20-Aug-03 20:10

Hi all

How to get a file's last modified time?

Thanks

Re: File Access Time

Dominik Reichl20-Aug-03 20:52

Dominik Reichl

20-Aug-03 20:52

Use the CreateFile Windows API function to get a handle to the file you wish to retrieve the date/time. Then use this function:

BOOL GetFileTime(
  HANDLE hFile,                 // handle to the file
  LPFILETIME lpCreationTime,    // address of creation time
  LPFILETIME lpLastAccessTime,  // address of last access time
  LPFILETIME lpLastWriteTime    // address of last write time
);

Hope that helps Big Grin | :-D

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: File Access Time

vcplusplus21-Aug-03 2:45

vcplusplus

21-Aug-03 2:45

CFileStatus status;<br />
CFile::GetStatus("C:\\config.sys", status);<br />
CTime tm = status.m_mtime;

read file from end to beginning

rohit.dhamija20-Aug-03 19:47

rohit.dhamija

20-Aug-03 19:47

Dear All,

I am developing an application in MFC VC++ Version 6.0 for Windows 2000.
I have a structure of format
//////////////////////////
struct ren
{
char src[150];
char desc[150];
};
//////////////////////////

I am fillng this structure with some values and then store this structure in a file for unfixed number of times (there may be more than

1000 entries and at same time no entry) during my program execution.

And at an click of event i read this file as
/////////////////////////////////////////////////
OFSTRUCT of;
HFILE hfile = OpenFile(RenFile,&of,OF_READ);
do
{
n=_lread(hfile,(char *)&ren,sizeof(ren));
....................................
....................................
....................................

}
while(n!=0);
_lclose(hfile);
/////////////////////////////////////////////////

This piece of code reads the structure from the beginning of file till END OF FILE structure by structure. Now I want to it to read the other way round!!
ie. I want to read the file from last structure to the beginning of file in an efficient manner.
ie.
if the file containts the entries
ram kali--------(1)
hari kumar--------(2)
lal singh --------(3)
the file should read 3 structure first , then second and then first.

Please send your useful suggestions.

Feel free to ask any further queries in this regards,

Thanks
Rohit Dhamija

Re: read file from end to beginning

igor196020-Aug-03 20:29

igor1960

20-Aug-03 20:29

MapViewOfFile.

"...Ability to type is not enough to become a Programmer. Unless you type in VB. But then again you have to type really fast..."
Me

Re: read file from end to beginning

rohit.dhamija20-Aug-03 20:50

rohit.dhamija

20-Aug-03 20:50

"Ability to type is not enough to become a Programmer. Unless you type in VB. But then again you have to type really fast..."
What do u mean by this ????? Sigh | :sigh:

Re: read file from end to beginning

igor196020-Aug-03 21:23

igor1960

20-Aug-03 21:23

This is my Logo. No offence buddy -- You are C++ guy anyway.

Regards

"...Ability to type is not enough to become a Programmer. Unless you type in VB. But then again you have to type really fast..."
Me

Re: read file from end to beginning

J. Dunlap20-Aug-03 21:35

J. Dunlap

20-Aug-03 21:35

lol

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

Re: read file from end to beginning

Member 42425920-Aug-03 22:20

Member 424259

20-Aug-03 22:20

Please go through the _lseek function

Thanx
TAKE CARE

Re: read file from end to beginning

Member 42425920-Aug-03 22:21

Member 424259

20-Aug-03 22:21

do u want the algo ???

Thanx
TAKE CARE

Re: read file from end to beginning

rohit.dhamija20-Aug-03 22:53

rohit.dhamija

20-Aug-03 22:53

no the algo , i just wanted to find some ways to accomplish the task and find out the most efficient way to do.

Re: read file from end to beginning

rohit.dhamija20-Aug-03 23:03

rohit.dhamija

20-Aug-03 23:03

I am using

fseek( stream, 0L, SEEK_END);
fseek( stream, -sizeof(FileAdd), SEEK_CUR);

to go to the last structure and will then go the second last and so on....

Please suggest some other alternatives.

Rohit

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.