Managed C++/CLI

Re: C++/CLI: Formatting outputs (decimal places, hexadecimal, case notation)

20-Dec-08 10:22

Hi, when I was programming in console mode if I needed to display only 2 decimal values of a variable (e.g. Variable1) I would write this simple code:

cout << "Variable1 = " << setprecision (2) << fixed << Variable1 << endl;

But now in C++/CLI environment how can I display this value inside a textbox showing only 2 decimal values?
Can I add some attributes to the following code?

textBox1->Text= Variable1.ToString();

And what about if I wanted to display it in Hexadecimal and/or in Upper case notation?

Many thanks in advance!

Luc Pattyn20-Dec-08 11:00

Re: C++/CLI: Formatting outputs (decimal places, hexadecimal, case notation)

20-Dec-08 11:00

so you decided to use some type's ToString() method but you did not consider reading up about it? Unsure | :~

Luc Pattyn [Forum Guidelines] [My Articles]

Fixturized forever. Confused | :confused:

J_E_D_I20-Dec-08 22:53

Re: C++/CLI: Formatting outputs (decimal places, hexadecimal, case notation)

20-Dec-08 22:53

Any advice please on where to find more info on this?
Thanks

Rob Graham21-Dec-08 3:54

Rob Graham

21-Dec-08 3:54

Object.ToString() has several overloads. some accept formatting instructions and culture specifications. You can get help on MSDN (and in visual studio help). You should consult the ToString(0 documentation for the particular type you are concerned with, as the base class virtual methods are often overridden. The help for Int32[^] is typical, and should shed light on your question. There are many links to additional details on formatting in the help article.

Re: C++/CLI: Formatting outputs (decimal places, hexadecimal, case notation)

J_E_D_I21-Dec-08 6:11

Re: C++/CLI: Formatting outputs (decimal places, hexadecimal, case notation)

21-Dec-08 6:11

In reply to my question...

textBox1->Text= Variable1.ToString("N0"); //shows value with 0 decimal places
textBox1->Text= Variable1.ToString("N2"); //shows value with 2 decimal places
textBox1->Text= Variable1.ToString("X");  //shows value in Hexadecimal notation (capital case)
textBox1->Text= Variable1.ToString("x");  //shows value in Hexadecimal notation (normal case)

Hope it helps somebody out there like me. I am really amazed there isn't a decent manual on these very basic things... It must all be there on MSDN but I find it the most impossible reference to consult.

TigerNinja_24-Dec-08 19:04

TigerNinja_

24-Dec-08 19:04

MSDN string formatting instructions are tricky to find.

Pro tip:
Don't use ms search engine, it's horrible. use google with site:msdn.....com helper.

Google Query used: c# ToString format decimal site:msdn.microsoft.com

First link I found: (Almost)
http://msdn.microsoft.com/en-us/library/fzeeb5cd.aspx[^]

Linked from first: (We have a winner):
http://msdn.microsoft.com/en-us/library/dwhawy9k.aspx[^]

R.Bischoff

Tengas un buen dia

Converting COM object to actual unmanaged type pointer

sajanemmanuel14-Dec-08 18:50

sajanemmanuel

14-Dec-08 18:50

Deal all,
I just want to know how can I convert an object to a user defined type pointer in managed C++. I will elaborate my situation. I want to use an ActiveX control in a windows form application written in C#. When we add an ActiveX into a project VS generates the RCW objects. In my case it is

private AxXVIDEOOCXLib.AxXVideoOCX axXVideoOCX1;

Now I will get the underlying ActiveX object using the function
Object obj = axXVideoOCX1.GetOcx();

Now I need to pass this object into a managed C++ dll(.net component). Inside this dll I have a function with prototype in an unmanaged class as follows

int CVideoRecorderCtrl::AddOCXHandle(CXVideoOCX* OCXHandle)

Can any one commment whether my approach is correct? If yes my question is yet to come.

The class CXVideoOCX is the class of ActiveX component. Is there any successful way so that I can convert this COM object to its actual unmanaged type..I am searching for a solution for past 1 week. I will be really really thankful if anyone have any comments on these.

Creating a Registry Value in C++/CLI environment

J_E_D_I13-Dec-08 8:36

Re: Creating a Registry Value in C++/CLI environment

13-Dec-08 8:36

I was wondering if anybody could give me hand solving this problem. I need to save a DWORD value (DesiredValue) in a registry key and this was the syntax I was using (successfully) in console environment.

DWORD DesiredValue;

// Creates Desired Registry Key 
	HKEY Xtmpkey;
	DWORD dwDisp = 0;
	LPDWORD xlpdwDisposition = &dwDisp;
	DWORD dwVal = DesiredValue; 
	// Desired Path for the Registry Key 
	RegCreateKeyEx(HKEY_CURRENT_USER, L"SOFTWARE\\MyPath", 0L,NULL, REG_OPTION_NON_VOLATILE,    KEY_ALL_ACCESS, NULL, &Xtmpkey,xlpdwDisposition);

// Creates Desired Value
RegSetValueEx (Xtmpkey, L"Desired_Value_Name", 0L, REG_DWORD,(CONST BYTE*) &dwVal, sizeof(DWORD));

Now that I am porting the software into C++/CLI environment it returns the following errors:

Error 1 error LNK2001: unresolved external symbol "extern "C" long __stdcall RegCreateKeyExW(struct HKEY__ *,wchar_t const *,unsigned long,wchar_t *,unsigned long,unsigned long,struct _SECURITY_ATTRIBUTES * const,struct HKEY__ * *,unsigned long *)" (?RegCreateKeyExW@@$$J236YGJPAUHKEY__@@PB_WKPA_WKKQAU_SECURITY_ATTRIBUTES@@PAPAU1@PAK@Z)

Error 2 error LNK2001: unresolved external symbol "extern "C" long __stdcall RegSetValueExW(struct HKEY__ *,wchar_t const *,unsigned long,unsigned long,unsigned char const *,unsigned long)" (?RegSetValueExW@@$$J224YGJPAUHKEY__@@PB_WKKPBEK@Z)

Error 3 fatal error LNK1120: 2 unresolved externals

What am I doing wrong?

Thanks in advance.

Mark Salsbery13-Dec-08 10:01

Mark Salsbery

13-Dec-08 10:01

You need to link to Advapi32.lib.

#pragma comment(lib, "Advapi32.lib")

Or, since it's managed code, you could use the Microsoft.Win32.Registry Class[^],
which is a tad easier to use than the Win32 APIs.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Creating a Registry Value in C++/CLI environment

J_E_D_I13-Dec-08 17:33

Re: Creating a Registry Value in C++/CLI environment

13-Dec-08 17:33

Mark Salsbery wrote:
You need to link to Advapi32.lib.

#pragma comment(lib, "Advapi32.lib")

You are a "C"enius, it works! I wish one day I could be as smart.
Big Grin | :-D

Mark Salsbery14-Dec-08 9:40

Mark Salsbery

14-Dec-08 9:40

It's all in the documentation Poke tongue | ;-P

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Creating a Registry Value in C++/CLI environment

leonigah18-Dec-08 23:04

leonigah

18-Dec-08 23:04

using namespace Microsoft::Win32;
Registry::SetValue("HKEY_CURRENT_USER\\SOFTWARE\\MyPath", "Desired_Value_Name", "Value");

Nigah M Manzoor

How to check availability of internet connection

anveshvm11-Dec-08 3:00

Re: How to check availability of internet connection

11-Dec-08 3:00

Hi I have an SQL query which is to be executed from the server. Just before executing, I am checking if the internet is available or not.

I am using InternetGetConnectedState api to implement this.

But this call returns true, for 2-3 seconds after the network connection is lost. This causes the application to hang.

Pls verify my code and check if it is the appropriate code

---------------------------------------------------

[DllImport("wininet.dll",
SetLastError=true,CharSet=CharSet::Unicode,ExactSpelling=true,
CallingConvention=CallingConvention::StdCall)]
static bool InternetGetConnectedState(int &Description, int ReservedValue ) ;

bool IsConnectedToInternet()
{
int Desc ;
return InternetGetConnectedState(Desc, 0 ) ;
}

if (IsConnectedToInternet())
{
mysql_query(mysqlConnectorObject,sqlQuery);
return mysql_store_result(mysqlConnectorObject);
}
else
{
MessageBox::Show("Not connected");
}

----------------------------------------------------

Thanks in advance

Anvesh

Luc Pattyn11-Dec-08 3:16

Re: How to check availability of internet connection

11-Dec-08 3:16

Hi,

InternetGetConnectedState() is the best way I know to look at the Internet connection state.

You are saying it shows a slightly outdated state, but that should not be too bad. Anyway,
the connection could be lost right after you call the function, so the code that follows must
survive that anyway. Hence, use asynchronous code (on a separate thread) and give whatever you
are trying to do a timeout.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Fixturized forever. Confused | :confused:

anveshvm11-Dec-08 4:12

Re: How to check availability of internet connection

11-Dec-08 4:12

Thank you very much.....

Can you pls tell me how to set the time limit when starting a new thread.

Can you also suggest the most suited class to do this? I mean whether it is backgroundworker, threadpool or thread class?

Luc Pattyn11-Dec-08 4:36

Re: How to check availability of internet connection

11-Dec-08 4:36

anveshvm wrote:
how to set the time limit

you either perform calls that support a time limit, or you should launch a (one-shot) timer, which:
- you cancel again when the operation succeeds
- and if the timer fires, you stop the timer and cancel the thread

anveshvm wrote:
backgroundworker, threadpool or thread?

whatever fits your circumstances best; since you may have to abort it, threadpool could not be the right choice though.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Fixturized forever. Confused | :confused:

anveshvm11-Dec-08 4:42

Re: How to check availability of internet connection

11-Dec-08 4:42

Thank you Luc Pattyn.... I will try that way. Smile | :)

Luc Pattyn11-Dec-08 13:29

How to check the return value of a messagebox

11-Dec-08 13:29

Hi,

I just discovered this article[^] that may interest you.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Fixturized forever. Confused | :confused:

anveshvm11-Dec-08 2:52

Re: How to check the return value of a messagebox

11-Dec-08 2:52

I have written a code to check the return value of a message box. But it doesn't work .

My code is
--------------------------------------

DialogResult^ res = MessageBox::Show("Network connection failed.,"Error in connection",MessageBoxButtons::RetryCancel,MessageBoxIcon::Warning,MessageBoxDefaultButton::Button1);

if (res == System::Windows::Forms::DialogResult::Cancel)
{
Application::Exit();
}
else if (res == System::Windows::Forms::DialogResult::Retry)
{
continue;
}

---------------------------------------------------------

Here both the if condition fails...

In immediate window, the value of res is {...}

Pls check it

Thanks in advance

Anvesh

Luc Pattyn11-Dec-08 3:10