C / C++ / MFC

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 7:15

I created structures to pass arrays of data to SQL Server to write a user record with no problem.

So I thought using the same method would work in reverse for retrieving an array of user records to populate a List Box.

But I can't figure out how to initialize the structure in my class as an array. I can Initialize the structure as a single record, and pass it to the function.

I created a sql server call to get the record count first, so I can size the array.

I thought it would be written like this ...

dbUA.UA_LISTBOX *uaList = new dbUA.UA_LISTBOX[dwCount];

My Class Strucure and function

CSS

class DB_UserAccount {

public:

    struct UA_Listbox {
        INT             iUserID;
        WCHAR           *szFirstName;
        WCHAR           *szLastName;
        WCHAR           *szAccountName;
    } UA_LISTBOX;

BOOL _get_UserAccount_Listbox_Count( DWORD &dwCount );
BOOL _get_UserAccount_Listbox_Info( UA_Listbox &pzUserList );

//My Function that calls the class
BOOL UserAccount_Index::_load_UserAccount_Index_Listbox( void )  
{
	DB_UserAccount dbUA;
	DWORD dwCount;
	dbUA._get_UserAccount_Listbox_Count( dwCount );	


	return TRUE;
}

Code-o-mat30-Dec-11 8:30

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 8:30

turn your UA_Listbox struct into a class and add a constructor:

CSS

class UA_Listbox {
public:
  INT             iUserID;
  WCHAR           *szFirstName;
  WCHAR           *szLastName;
  WCHAR           *szAccountName;

  UA_Listbox() //Standard constructor, do the initialization of members here, like:
  : iUserID(0)
  , szFirstName(NULL)
  , szLaszName(NULL)
  , szAccountName(NULL)
  {
  }
} UA_LISTBOX;

If you mean, you want to initialize the items differently (so every item gets different values) then you won't be able to do it that way, you will need to have a pointer-array and add the items one-by-one, eg:

UA_Listbox **uaListBoxPtrArray;
...
uaListBoxPtrArray = new UA_ListBox*[dwCount];
for (DWORD i = 0; i < dwCount; i++)
{
  uaListBoxPtrArray[i] = new UA_Listbox;
  uaListBoxPtrArray[i]->iUserID = ...//initialize the members as you need to, maybe add a constructor
                                     //for passing the values...
}

You might try using std::vector too, like:

std::vector<UA_Listbox *> arListBox;
for (DWORD i = 0; i < dwCount; i++)
{
  arListBox.push_back(new UA_Lostbox(...));
}

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

jkirkerx30-Dec-11 9:15

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 9:15

Code-o-mat wrote:
turn your UA_Listbox struct into a class and add a constructor:

So make the class first. I'am storing different values in it

01 Joe Smoe jSmoe
02 John Doe jdoe

Then make the constructor

Are vectors the preferred way of packaging data?

Code-o-mat30-Dec-11 9:33

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 9:33

jkirkerx wrote:
So make the class first. I'am storing different values in it

01 Joe Smoe jSmoe

02 John Doe jdoe

Then make the constructor

I'm not sure i understand what you mean. Basicaly, structs and classes are the same in C++ except that the default access type for a class is "private" while for a struct it's "public". It's just personal preference -i guess- that i only use struct when all it does is to group a few data members together, but if it has a constructor/destructor or other methods defined, i use class.

I don't think there's a "prefered" way of "packaging data" as you said, it all depends on your needs, your requirements, your habits... you might as well use a linked list, a bi-directional linked list, hell, you could use a tree or a hash table if that is what best suits you.

P.S. if you use a pointer array, don't forget to delete your items before deallocating the struct itself.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

jkirkerx30-Dec-11 10:01

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 10:01

I wrote all the hard functions for my program first, like registry values, encrypting, creating a database, downloading programs, SQL ODBC Calls for Data.

Now I'm gluing it all together with the GUI interfaces, so because I came from VB Windows and the web world, I'm in new territory here as to best practices. I don't have any preferences yet, and I had no idea there was so many ways to do it.

Let me finish my Dialog Box first, so I can populate it and read the data entered, then I'll get back to the listbox and sql data packaging.

Thanks for the suggestions, I'm sure one of them will work out for me.

Code-o-mat30-Dec-11 10:06

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 10:06

All right, good luck. Smile | :)

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

jkirkerx31-Dec-11 8:51

Re: Intializing a structure array to store SQL Results from a class

31-Dec-11 8:51

Did I get this right?

I'm missing something here, I get a single structure, and not an array structure. I just keep writing the data to the same single structure. I must be missing something in the class, but I'm not sure what. Or maybe I didn't initialize it right.

This is for populating the array

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS) {
	UA_Listbox **uaPtr;
	uaPtr = new UA_Listbox*[dwCount];
	INT	i = 0;
	INT	pzUserID;
	WCHAR	pzFirstName[cbFirstName];
	WCHAR	pzLastName[cbLastName];
	WCHAR	pzUserName[cbUserName];						

	while (SQLFetch(hstmt) == SQL_SUCCESS) {
		// Get Data from the Table
		SQLGetData(hstmt, 1, SQL_C_ULONG, &pzUserID, 0, NULL );
		SQLGetData(hstmt, 2, SQL_C_WCHAR, &pzFirstName, cbFirstName, NULL );
		SQLGetData(hstmt, 3, SQL_C_WCHAR, &pzLastName, cbLastName, NULL );
		SQLGetData(hstmt, 4, SQL_C_WCHAR, &pzUserName, cbUserName, NULL );

		// Transfer Pointers to Structure
		uaPtr[i] = new UA_Listbox;
		uaPtr[i]->iUserID = pzUserID;
		uaPtr[i]->szFirstName = pzFirstName;
		uaPtr[i]->szLastName = pzLastName;
		uaPtr[i]->szAccountName = pzUserName;
		++i;
	}

This is the class

class UA_Listbox {

public:

    INT             iUserID;
    WCHAR           *szFirstName;
    WCHAR           *szLastName;
    WCHAR           *szAccountName;

    UA_Listbox():
        iUserID(0),
        szFirstName(NULL),
        szLastName(NULL),
        szAccountName(NULL)
    {
        // Constructor

    }

    ~UA_Listbox()
    {
        // Deconstructor

    }

};

Code-o-mat31-Dec-11 8:57

Re: Intializing a structure array to store SQL Results from a class

31-Dec-11 8:57

jkirkerx wrote:
uaPtr[i]->szFirstName = pzFirstName;
uaPtr[i]->szLastName = pzLastName;
uaPtr[i]->szAccountName = pzUserName;

You store pointers to the same buffers N times.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

jschell30-Dec-11 8:35

jschell

30-Dec-11 8:35

Your database layer should be distinct from your display layer.
Your display layer uses the database layer. There is no display information/design in the database layer (noting of course that the application design of a simple app might seem to drive directly through the two layers.)

jkirkerx wrote:
I thought it would be written like this ...

What exactly is the question?

You need a pointer. You need to new an array. Then you initialize each member in the array.

If you are asking how to access a member of the array then you do it as
uaList[0].iUserID
uaList[1].iUserID
etc.

(Presumably you are also providing code to clear up every single allocation.)

Also given that you are using C++ why are not just using a straight forward class with string members?

Formatting suggestions.
- Don't put underscores in the middle of names.
- Don't put underscores at the beginning of method names.
- If a method belongs to a class then don't prefix the class name to the method.

Re: Intializing a structure array to store SQL Results from a class

jkirkerx30-Dec-11 9:22

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 9:22

I probably should of just asked what the preferred method of packaging data is.

I'm still in c++ 100 here, I started in vb.

in vb, I would of just typed

Dim UserInfo(6, TheCount) As String
UserInfo = Users.Get_ListBoxInfo()

I'll try the post above and see how it works.

Vaclav_30-Dec-11 12:24

Vaclav_

30-Dec-11 12:24

Minor suggestion
It is either struct - structure or an array of ... whatever.
Or an array of struct.
It appears that you are after single struct of strings.
Anyway, just a suggestion since you asked what is prefered.
And a really small suggestion - if the function finds a count of items, the return value should be the count and not just true / false. Unless of course you really do not need the count.
Vaclav

Re: Intializing a structure array to store SQL Results from a class

jkirkerx30-Dec-11 12:40

Re: Intializing a structure array to store SQL Results from a class

30-Dec-11 12:40

I thought I had to dimension the array first, guess that's not needed if I write better code.

Well here goes, finished my dialog form, so I'm back to the array now.

jschell31-Dec-11 13:10

jschell

31-Dec-11 13:10

jkirkerx wrote:
I thought I had to dimension the array first

You might want to experiment with some simpler arrays first. I would suggest an array of ints then an array of strings (the string class, not a char*).

Allocate the arrays, assign values to members of the array, then sequence through the array to verify, then deallocate the array.

After that your implementation is just a variation on the above (especially since string is a class so you will have already created an array of classes.)

Re: Intializing a structure array to store SQL Results from a class

jkirkerx31-Dec-11 13:14

31-Dec-11 13:14

That's a good idea. I will start with some small simple arrays first and get the hang of it in c++, then take it from there.

Thanks jschell

UNIT how to convert int

dlsyaim29-Dec-11 21:59

dlsyaim

29-Dec-11 21:59

In MFC, UNIT how to convert an int,can you help me? Master

_Flaviu29-Dec-11 22:03

_Flaviu

29-Dec-11 22:03

Just like that :

C++

int i = 0;
UINT u = 9;
i = (int)u;
TRACE("%d\n",i);

C++

int i = 0;
UINT u = 9;
u = (UINT)i;
TRACE("%d\n",u);

Richard MacCutchan29-Dec-11 22:09

Richard MacCutchan

29-Dec-11 22:09

Assuming that you mean UINT rather than UNIT you just need to cast it thus:

C++

UINT uIntValue = 100;
int intValue = uIntValue;

Be aware that any values greater than 2147483647 (0x7FFFFFFF) will be negative in the resulting integer.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

dlsyaim29-Dec-11 22:26

dlsyaim

29-Dec-11 22:26

Thank you, I understand. But the source is so written.

for (UINT uiLineStyleCmd = ID_LINE_STYLE_1;
uiLineStyleCmd <= ID_LINE_STYLE_10;
uiLineStyleCmd++)
{
int iIndex = pMenuPopup->GetMenuBar ()->CommandToIndex (uiLineStyleCmd);
if (iIndex >= 0)
{
pMenuPopup->GetMenuBar ()->m_bDisableSideBarInXPMode = TRUE;
//----------------------------
// Obtain item text and style:
//----------------------------
CString strText = pMenuPopup->GetMenuBar ()->GetButtonText (iIndex);
UINT uiStyle = pMenuPopup->GetMenuBar ()->GetButtonStyle (iIndex);

//------------------
// Calc. line width:
//------------------
int nWidth = uiLineStyleCmd - ID_LINE_STYLE_1 + 1;

//-------------------
// Replace menu item:
//-------------------
pMenuPopup->GetMenuBar ()->ReplaceButton (uiLineStyleCmd,
CLineStyleMenuItem (nWidth,
uiLineStyleCmd,
strText,
uiStyle & TBBS_CHECKED));
}

Richard MacCutchan29-Dec-11 22:51

Richard MacCutchan

29-Dec-11 22:51

Firstly, please use <pre> tags around your code and ensure that it is formatted properly. Secondly, what is your problem?

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman