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I've heard of the ADODB abstraction class, and I've seen it used successfully in VB codes (loading as bytes), but would that come under managed C++?
thanks
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No, the class I referred to is not managed code.
It is a crappy thing, but it's life -^ Carlo Pallini
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I'm an experienced mainframe developer familiar with old world languages (COBOL, Assembler etc). I've recently written a couple of C batch programs, now successfully in production. I've now been briefed to write a C subroutine, for use by non C main programs, and have come across a fundamental problem: How do I exit a C subroutine? Is this a design issue ie should the code flow return to the top level where a normal'return' will take control back to the calling code or is there more to it?
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The subroutine in C language is called as function.
Do you mean that you have one function which calls another function and soon?
If so, yes you have to keep returning from the functions, either using the return statement or by reaching the end of the function, till you reach the top level function.
Whenever a function calls another function, it puts the return address on the stack just before the second function is called. So if you have a deep level of function calls, the stack has to unwinded properly.
«_Superman_»
I love work. It gives me something to do between weekends.
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Thanks for your reply; no, my query was about a seperately compiled piece of non-'C' code calling my piece of seperately compile 'C' code. But I think your answer was correct; I need to treat my code as a function so that control returns to the caller by going up the stack and exiting via the final 'return'.
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Andrew Jenkinson wrote: How do I exit a C subroutine
The 'return' statement. Either 'return' for a void function, or 'return value for a non-void function. A void function can also return by reaching hte end of the function. Here are some examples:
void VoidFn(int value)
{
if (value < 0) return;
printf("%d", value);
}
int NonVoidFn(int value)
{
if (value >= 0) return value;
return -value;
}
You can return from anywhere in a C function, but many people recommend using only a single exit point. Personally, I take the pragmatic approach - if it makes sense to return earlier than the end of a function, then just do it.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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If you've done assembler programming, you should find C very familiar, or easy to pick up, since it mostly operates in a very similar way. You can even view the high-level constructs as wrappers or macros *
Mind you, I'm amazed (or horrified) that wherever you work is just moving from COBOL into C (legacy apps I guess). You've a lot of catching up to do...
[ * OK, that's a huger over-simplification with modern compilers, but for the most part you can convert assembler into C very easily, and vice versa ]
There are three kinds of people in the world - those who can count and those who can't...
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You're right, I've quite enjoyed using C, though I still feel more in control working in assembler. Guess it's an age thing  These last 10 years or so have been spent on migration projects, working for companies moving away from their legacy applications which is why I'm picking up things like C and .NET (I'm an MCP & MCTS now, for all the good it does me!) My specialisation is a mainframe commisioned by NASA as a number crunching machine for the moon project, which shows its age. These machines tend to run large applications which take a lot of redeveloping which is why some still exist.
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And there was me thinking NASA had the latest, greatest systems on the planet  Although, I have seen pictures of the shuttle with several laptops runnning the "real" flight code, and interfacing to the outdated flight computers, so I suppose I shouldn't be surprised.
As an amateur astronomer and spaceflight fan I've been following the technology developments for a long time - in fact I started programming about a year after Armstrong and Aldrin stepped onto the moon. Even then the hardware being used was a bit behind the leading edge, although I can well understand that reliability and reproducability play a huge part in choosing flight hardware. I bet there's still some code running today that was written in the 60's... 
Anyway, I'd highly recommend a few home-brew projects to get more familiar with C and C++ - there must be a few ideas you've been thinking about for years that you could try out, and use to learn the new stuff you'll more than likely need in years to come. I spend all day writing "work" code, then relax in the evenings by writing "my" code. I can mess about on whatever I want, learn new stuff, and it doesn't matter if it's never finished.
Although, I suppose I'm lucky in my job - a bit of C# for tools development and non-critical code, C++ for the proper engine coding, a bit of Python thrown in, and assembler or IL for those "shave off the last nanosecond" critical bits. And we get loads of cool toys as well
There are three kinds of people in the world - those who can count and those who can't...
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Hi All
I need to connected Mysql through mfc code.I have found article which is very good.They all are advice to insttal drive ODBC.I do it and it's working.But i have a question about that,can i make connection without any external driver.
Plz advice me
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I am not overly familiar with ODBC but I have had to write applications that need to communicate with a database.
Check out
the MySQL C API
http://dev.mysql.com/doc/refman/5.0/en/c.html[^]
the C++ wrapper for the MySQL C API
http://tangentsoft.net/mysql++/[^]
Also if you are communicating with a web server database consider writing a server side web script to handle database queries and communicate with it with.
URLDownloadToCacheFile
http://msdn.microsoft.com/en-us/library/ms775122(VS.85).aspx[^]
This might or might not be reasonable depending on what you are trying to accomplish, but it is probably the quickest and easiest way to get the job done for basic web database queries.
Chris Smith
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thanks for reply.You have given me this link but sorry it's not use for me.
My question is,Can i make connection without any ODBC Driver?
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These are the available connectors[^].
As you see, there is a C++ connector - but that uses classes that MySQL provide, not the MFC classes. I think that's the closest to what you're asking for.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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hai all,
in vc++ 6.0, for a dialog based application, is it possible to hide its instance on task bar?
please let me know any clues on how to achieve this.
thanks in advance.
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Look into WS_EX_APPWINDOW
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How to load dynamically latitude, longitude values from my Exe to Search box (maps.google.com) browser.
Thanking all of you in Advance.
Regards
tgm.arjun
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A BHO, perhaps. You might also check to see if the browser has a COM (i.e., automation) interface.
"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown
"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
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I'm still new to learning C++ (learned some of C# first) and having a hard time knowing what the preferred way to handle this situation is.
I have a class that has a constructor that does some initialization work. If this initialization fails, I want to inform the program that this is not a valid object to use. I created my constructor to throw an exception as that is really the only way that I know how (since constructors can't return values).
Now, in my program I am trying to create an object of my class so I put a try/catch block around it. This worked great until I realized that no code outside of the try/catch block would be able to use that object because it is out of scope.
It appears that there is no good way to use global variables that has a constructor that throws an exception. So what is the normal procedure for this type of situation. Do you normally create a pointer to the object so that you can use the new keyword to create the object? If so, is there a way to prevent someone from creating an object and not a point to your class?
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hpjchobbes wrote: So what is the normal procedure for this type of situation. Do you normally create a pointer to the object so that you can use the new keyword to create the object?
Yes, that's what I'd do.
hpjchobbes wrote: If so, is there a way to prevent someone from creating an object and not a point to your class?
Make the constructors private and add a static method that returns a newly allocated object:
class C
{
public:
static C* MakeNewC() { return new C; }
private:
C()
{
}
};
int main()
{
C c;
C* pC = C::MakeNewC();
}
HTH!!!
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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I'm trying to automate IE. That piece of code works fine on my VC++ desktop computer with vista and IE8. The problem is it's not working on my laptop (vista + IE7). There is no error message. According to the messageboxes, the code stops when trying to get the READYSTATE statement. I mean I got the first messagebox ("navigation ...") but not the second one ("readystate ..."). Plus the browser doesn't close as it is supposed to do.
I don't know if it's related but I compiled the project using the /MT command and I didn't install the Visual C++ 2008 Redistributable Package (x86) on the laptop. This is because I want to run this code as a single exe.
Can please someone help me to understand wht is going on ?
Here is my code :
#include "stdafx.h"
#include "Exdisp.h"
#include "mshtml.h"
#include "windows.h"
#include "winerror.h"
int _tmain(int argc, _TCHAR* argv[])
{
if (SUCCEEDED(OleInitialize(NULL)))
{
IWebBrowser2* pBrowser2;
IHTMLDocument2* Doc;
IDispatch* pHtmlDispatch;
READYSTATE rState;
DWebBrowserEvents2* pEvents;
HRESULT hr;
CoCreateInstance(CLSID_InternetExplorer, NULL, CLSCTX_LOCAL_SERVER,
IID_IWebBrowser2, (void**)&pBrowser2);
if (pBrowser2)
{
VARIANT vEmpty;
VariantInit(&vEmpty);
BSTR bstrURL = SysAllocString(L"http://www.google.com");
hr = pBrowser2->Navigate(bstrURL, &vEmpty, &vEmpty, &vEmpty, &vEmpty);
if (SUCCEEDED(hr))
{
MessageBox(NULL, TEXT("Navigation successful"),TEXT("Status"),MB_OK);
pBrowser2->put_Visible(VARIANT_TRUE);
do
{
hr = pBrowser2->get_ReadyState(&rState);
}while(hr == S_OK && rState != READYSTATE_COMPLETE);
MessageBox(NULL, TEXT("ReadyState Complete"),TEXT("Status"),MB_OK);
}
SysFreeString(bstrURL);
hr = pBrowser2->get_Document(&pHtmlDispatch);
if (SUCCEEDED(hr) && (pHtmlDispatch != NULL))
{
MessageBox(NULL, TEXT("Dispatch obtained"),TEXT("Status"),MB_OK);
hr = pHtmlDispatch->QueryInterface(IID_IHTMLDocument2, (void**)&Doc);
if (SUCCEEDED (hr) && (Doc != NULL))
{
MessageBox(NULL, TEXT("Document obtained"),TEXT("Status"),MB_OK);
Doc->Release();
}
else
{
return hr;
}
pHtmlDispatch->Release();
}
else
{
return hr;
}
pBrowser2->Quit();
pBrowser2->Release();
}
OleUninitialize();
}
return 0;
}
modified on Friday, July 3, 2009 2:40 PM
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I do wonder if it's something to do with not having an active windows message loop (which COM uses for marshalling calls with single threaded apartments, IIRC) - I mean, you do while the message box is active, but not afterwards - maybe the laptop's slower at getting to the readystate=complete? After all, IE7 is slow as a dog compared to real browsers, even IE8!
So - might be worth adding message dispatch in the do/while loops?
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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Hi,
I typed in the following code and found it to compile and run ok (using VS 2003).
<br />
#include < iostream ><br />
using namespace std;<br />
<br />
template <class T , class U> void swapa(T & a, U & b)<br />
{<br />
cout << a << " " << b;<br />
}<br />
<br />
int main()<br />
{ <br />
<br />
int x = 3;<br />
const double y =5.234;<br />
swapa < int , const > (x, y);<br />
<br />
return 0;<br />
}<br />
I am surprised of this as I did not declare the type explicitly in the invocation of swapa() where the comment is. Can someone pls explain?
Many thanks!
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minkowski wrote: template void swapa(T & a, U & b)
Isn't it
template void <class T, class U> void swapa(T & a, U & b)
?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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