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Any particular reason you chose to start with c++?
C# and VB.Net will provide a lot more examples of what you're after; particularly when it comes to Access.
"(I) am amazed to see myself here rather than there ... now rather than then".
― Blaise Pascal
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Can you use MFC?
With CDatabase and CRecordset classes your DB access would be more easy and simple!
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Don't recommend MFC for new developments the framework is going to become increasingly problematic now it's out of support and cracks have already opened up with current updates of Windows 10.
If you really feel it would be good to use at least make them aware of the issue going forward.
In vino veritas
modified 15-Mar-18 23:20pm.
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AFAIK is MFC not out of support. It is not enhanced anymore but bugs are (and will be probably) fixed.
But I can understand your suggestion to use it not for new projects.
From your (very good) answer to the initial question:
Quote: There is a class in C++ that acts much like VB strings called CString
CString is a MFC class and requires linking with the MFC libraries.
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leon de boer wrote: Don't recommend MFC for new developments the framework is going to become increasingly problematic now it's out of support and cracks have already opened up with current updates of Windows 10.
And where did you get this information from? Some "very secure source" from MSFT? Or?
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If you don't believe me then stop being lazy and ask on the microsoft forums, if you have a MSDN subscription go to support and see what it says.
The MFC source has been released & open sourced which gives you a clear indication of the commercial value, it comes free with Visual Studio 17 community edition.
You are still on version 14 and have been since 20 July 2015 and they managed the small update to deal with the Windows 10 issues which managed to get released with the last Visual Studio 17 update cycle on 6 March 2018. The update simply deals with legacy MFC calls that stopped working.
MFC is targetted to the legacy bridge path it will have no native access to the ever expanding Windows 10 API
Calling Windows 10 APIs From a Desktop Application - Windows Developer BlogWindows Developer Blog[^]
I should mention the old Win16 API still exist in windows 10 under much the same support and there are a lot of legacy programs that still work and there are also a lot that don't. I love the old 16bit API, I cut my teeth on it but I wouldn't recommend someone write a new development targeting it.
So we get into some tricky language about what is and what does support actually mean. I loved the above quote in the article
Or put a different way, there are no secret APIs being kept away from Windows developers.
We could put that another way, we have told you the API and we have no intention of adding it MFC but you can.
I will leave you to ponder thru all that and decide if I got it all wrong. I am not microsoft and I don't speak for them so ask them directly. As far as I know your old code will hopefully continue to work on Windows but you will have no access to the new features unless you write them yourself.
In vino veritas
modified 18-Mar-18 20:59pm.
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Put a debug point jsut after this line and look at string
Quote: SQLWCHAR* strSQL = (SQLWCHAR*)"SELECT Exchanges.[X Name], Exchanges.[X Full Name] FROM Exchanges;";
I am betting it comes out as garbage
Why... this code sequence below is a text string of char AKA 8 bits
Quote: "SELECT Exchanges.[X Name], Exchanges.[X Full Name] FROM Exchanges;"
I am betting that SQLWCHAR is a wide character AKA something that isn't 8 bits and you just forcibly typecast it.
I am guessing you have to forcibly typecast it because the compiler objected to you assigning it.
You need to do a quick update reading on how to write wide and unicode strings in C/C++
Working with Strings (Windows)[^]
I am guessing that text needed to be .. the L at the start is very important 
Quote: L"SELECT Exchanges.[X Name], Exchanges.[X Full Name] FROM Exchanges;"
Coming off VB you will have an issue that C++ won't hold your hand, strings are not held in both formats like they are in VB because it's slow and costs time and space. VB looks at which of the various forms it matches and will use that right one. There is a class in C++ that acts much like VB strings called CString which carries the strings in both form if you need training wheels, you could use it.
The other option is to become familar with #include <tchar.h> and the features it offers but don't mix it with CStrings if you go that path.
There are other bits that look suspiciously like you have forced typecast probably to get over a compiler error
I am looking at =====> (wchar_t*)dsnName
Go thru and work out what needs to be char and what needs to be wchar and write the constant strings in the correct form
In vino veritas
modified 15-Mar-18 23:19pm.
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Thanks very much for the help everyone.
One of the main reasons for using C++ in this case is the amount of realtime calculations that are designed into the app.
You're totally right about the strings!! The first thing I tried to do in C++ was get it to print 'Hello World' to the console window and I could figure out why that could be so bloody hard to do. Anyway, thanks for suggesting tchar.h. I will definitely spend some time with that. One of the more challenging things for me so far is just trying to find the library to be looking at.
We had considered going the MFC route but we're saving that as a last resort because it seemed very bloated. Thanks for the lack of support warning. Didn't know that.
Well, I did finally get it going with OLE DB. So well do some more testing and playing around with it but I think we're on our way.
Thanks for your help guy!!!
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Have you single-stepped through the code using the debugger? What is the value of rc along the way?
"One man's wage rise is another man's price increase." - Harold Wilson
"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
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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#include <iostream>
using namespace std;
const int size = 3;
class vector{
int v[size];
public:
vector();
vector(int *x);
friend vector operator * (int a, vector b);
friend vector operator * (vector b, int a);
friend istream & operator >> (istream &, vector &);
friend ostream & operator << (ostream &, vector &);
};
in the above code the i am having problem understanding the friend f^n Quote: friend istream & operator >> (istream &, vector &);
here's what i know, so istream is for input streaming of data & ostream for output, and does & epresents some kind of reference to function >> ?
It is really confusing, please explain.
Thank you.
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friend istream & operator >> (istream &, vector &);
That is just for telling the computer the extraction operator (>>) is friend of the vector class.
The reference (&) is part of the extraction operator signature, e.g.
istream & operator >> (istream & is, vector & v);
Because such a operator
- takes a reference to
istream and a reference to a vector as arguments. - returns a reference to a
istream.
Incidentally this the magic underneath the extraction operator chaining, for instance:
cin >> v >> i; ->
(cin >> v) >> i; ->
cin >> i; ->
cin;
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Hi
I have a class which derives from CScrollView and i have a message map in it whose base class is CScrollView as follows:
class MyClass : public CScrollView
{
public :
DECLARE_MESSAGE_MAP();
void OnButtonSelect();
void Init();
CButton m_button;
}
BEGIN_MESSAGE_MAP(MyClass , CScrollView)
ON_COMMAND(ID_FILE_PRINT, OnFilePrint)
ON_COMMAND(ID_FILE_PRINT_DIRECT, OnFilePrint)
ON_COMMAND(ID_FILE_PRINT_PREVIEW, OnFilePrintPreview)
ON_BN_CLICKED(1010, OnButtonSelect)
END_MESSAGE_MAP()
MyClass::Init()
{
m_button.Create(_T("Hi"),, BS_PUSHBUTTON, CRect(0, 0, 80, 20), m_cdRadViewer, 1010);
m_button.ShowWindow(SW_SHOW);
}
MyClass:OnButtonSelect()
{
AfxMessageBox(_T("hi, button Clicked"));
}
In the above code, when i click on button, OnButtonSelect() is not getting called even i added the button notification message in Message Map. After investigation i understood, the Base class mentioned in Message map and my class is from CScrollView and it cannot inherit the button features.
If this is true, how can i access the button message in my function.
I want to create the buttons in runtime and want to do some operation based on the button click.
Is it possible to notify in case if my class is derived from CScrollView?
modified 15-Mar-18 5:40am.
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In DECLARE_MESSAGE_MAP you have:
void OnButtonSelect();
but in BEGIN_MESSAGE_MAP you have:
ON_BN_CLICKED(1010, OnMyButtonClicked)
which is not defined.
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Sorry its typo. The same function available in .h and .cpp. I corrected it now.
But still not working.
modified 15-Mar-18 6:01am.
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You are setting the parent of your button to the m_cdRadViewer window. Then that window will receive the BN_CLICKED notfication instead of your MyClass instance window.
You have to pass the correct window:
m_button.Create(_T("Hi"), BS_PUSHBUTTON, CRect(0, 0, 80, 20), this, 1010);Note that I have also removed an additional comma which would make your code throw a compilation error.
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Hey, Many thanks. It was working fine if i give this as window in CButton Create. But on my window i am loading active x control and hence i am giving active x control object so that it will always render on top of the window.
If i give "this", the button will be visible, once i load the active x control, the control will be on top and button will go back and thats the reason i gave active x control object instead of "this"
I will investigate like how to render it on top of active x control window, by creating it on "this" window.
modified 15-Mar-18 7:14am.
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Jochen
Even i gave the style of my button as push_button, why it appears as flat one without any push behavior. I added the button to the main window by this. I dint even loaded the active x control but even then it looks like flat button. Even i click on that button there is no depth i can see on it, there is no response from the button.
for (int i = 0; i < 1; i++)
{
m_button[i].Create(_T("Hi"), BS_PUSHBUTTON | WS_CHILD, CRect(0, 250, 120, 300), this, 101);
m_button[i].ShowWindow(SW_SHOW);
}
My class is derived from CTabView. I dint added any view yet. Just on that window i created this button at the bottom , i mean on the tab control bar to simulate it as a tab.
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Sampath579 wrote: My class is derived from CTabView. I dint added any view yet. Just on that window i created this button at the bottom , i mean on the tab control bar to simulate it as a tab.
but CTabView and "the tab control bar" are different windows! Don't they?
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My class is just derived from CTabView. I dint add any view or functionality except adding a button. Even though they are different, during button creation i gave "this" (which one does it refer? tab control or TabView) as the parent window. If "this" refers to tabcontrol then it should behave normally. right? Even i want to add button on TabControl bar itself but not on view.
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I don't know why that happens. I have just tried it with a simple dialog based app and the button looks like those from the dialog template.
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You can see my window with tab control and the look of the button in below link. I just created a class which inherits from CTabView which created a window with tabcontrol and added a code to create a button at bottom of the window. But the button does not look like push button.
Imgur: The magic of the Internet[^]
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It looks exactly like a Pushbutton to me. Are you using the correct themes and version of the Windows Common Controls[^]?
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Instead of inheriting a class from CTabview, this time i inherited from CScrollView and created a button on it which you can see in below link. This button perfectly looks like pushbutton and when i click on the button, there is some interaction i can see, i.e., button movement in and out. You can even observe a border on this button since i clicked on it.
Imgur: The magic of the Internet[^]
I am not understanding how this behaviour is getting differ from a CTabView class to CScrollView class.
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I wonder if the problem is that the CTabView has not been designed to allow what you want. Perhaps you should switch to the underlying CMFCTabCtrl Class[^], and roll your own version.
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I created a class which inherits from CTabView as follows:
class CTabClass : public CTabView
{
void OnCreate()
{
m_CView = RUNTIME_CLASS(CDocumentView);
AddView(m_CView,_T("Tab1"));
AddView(m_CView,_T("Tab2"));
}
}
I want only one view for all the tabs. Is it possible in MFC?
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