Managed C++/CLI

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]

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anveshvm11-Dec-08 4:42

anveshvm

11-Dec-08 4:42

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

Re: How to check availability of internet connection

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.

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Luc Pattyn [Forum Guidelines] [My Articles]

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anveshvm11-Dec-08 2:52

anveshvm

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

Re: How to check the return value of a messagebox

Luc Pattyn11-Dec-08 3:10

Re: How to check the return value of a messagebox

11-Dec-08 3:10

anveshvm wrote:
DialogResult^ res

do you want the ^ there? DialogResult is a value type, isn't it?

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anveshvm11-Dec-08 3:31

anveshvm

11-Dec-08 3:31

Yeah.... I got it....

Thanks alot

Re: How to check the return value of a messagebox

Luc Pattyn11-Dec-08 3:43

How to call base class method

11-Dec-08 3:43

you're welcome.

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s196675m8-Dec-08 8:54

s196675m

8-Dec-08 8:54

From inside the overriden virtual function of a derived class, how can I call the base class function. The C# equivalent is base.SomeVirtualFunction(); I need VC++ managed equivalent.

Thank you.

Re: How to call base class method

Mark Salsbery8-Dec-08 9:51

Re: How to call base class method

8-Dec-08 9:51

public ref class baseclass
{
public:
    virtual void virtualmethod()
    {
    }
};

public ref class derivedclass : public baseclass
{
public:
    virtual void virtualmethod() override
    {
        baseclass::virtualmethod();
    }
};

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

Eytukan12-Dec-08 19:49

Eytukan

12-Dec-08 19:49

You know it's really funny. C++/CLI forum is serving every other forum. All platform related things are being asked here taking the burden off C# & VB.net forums, and also the OO questions, freeing up the C++ forum Big Grin | :-D

OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus

Best wishes to Rexx[^]

Re: How to call base class method

Mark Salsbery13-Dec-08 6:52

Getting HDD serial No in C++/CLI environment

13-Dec-08 6:52

This board is so dead it makes me Sleepy | :zzz:

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

J_E_D_I5-Dec-08 21:50

5-Dec-08 21:50

Hi, I had this code which worked beautifully in console mode, but now I am trying to convert the program into windows forms and the compiler returns the following error:

Error 1 error C3861: '_T': identifier not found

Any advice on how to solve this problem would be highly appreciated.

int GetHDDserialNo;

	//// Gets HDD serial No
	TCHAR volumeName[MAX_PATH];
	DWORD volumeSerialNumber;
	DWORD maxNameLength;
	DWORD fileSystemFlags;
	TCHAR systemName[MAX_PATH];

	GetHDDserialNo = GetVolumeInformation
		(
		_T("c:\\"),
		volumeName, MAX_PATH,
		&volumeSerialNumber,
		&maxNameLength,
		&fileSystemFlags,
		systemName, MAX_PATH
		);

	int SerialNumber = volumeSerialNumber;

Mark Salsbery6-Dec-08 6:12

6-Dec-08 6:12

J_E_D_I wrote:
'_T': identifier not found

#include <tchar.h>

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

J_E_D_I6-Dec-08 9:07

6-Dec-08 9:07

Thanks, I do not get that error anymore...but I get all those ones!

Error 1 error C2065: 'MAX_PATH' : undeclared identifier
Error 2 error C2065: 'DWORD' : undeclared identifier
Error 3 error C2146: syntax error : missing ';' before identifier 'volumeSerialNumber'
Error 4 error C2065: 'DWORD' : undeclared identifier
Error 5 error C2146: syntax error : missing ';' before identifier 'maxNameLength'
Error 6 error C2065: 'maxNameLength' : undeclared identifier
Error 7 error C2065: 'DWORD' : undeclared identifier
Error 8 error C2146: syntax error : missing ';' before identifier 'fileSystemFlags'
Error 9 error C2065: 'fileSystemFlags' : undeclared identifier
Error 10 error C2065: 'MAX_PATH' : undeclared identifier
Error 11 error C2065: 'maxNameLength' : undeclared identifier
Error 12 error C2065: 'fileSystemFlags' : undeclared identifier
Error 13 error C2065: 'systemName' : undeclared identifier
Error 14 error C2065: 'MAX_PATH' : undeclared identifier
Error 15 error C2078: too many initializers

Mark Salsbery6-Dec-08 9:36

6-Dec-08 9:36

What other header files are you including?

Those errors indicate windows.h is not included.

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

J_E_D_I6-Dec-08 19:58

6-Dec-08 19:58

Actually, windows.h is already included in the .cpp file...

These are the other header files I've got:

#include "stdafx.h"
#include "Form1.h"
#include tchar.h
#include vector
#include ctime
#include math.h
#include fstream
#include string
#include iostream
#include sstream
using std::dec;
using std::hex;
#include iomanip 
using std::setprecision; 
using std::setbase;
#include cstdlib
using std::atof;
#include windows.h
#pragma comment(lib, "user32.lib")
#include stdio.h
#include cstdio
#include strsafe.h
using namespace Ex22_01;

(Note: I had to remove < and > from the directives as otherwise it would not show up in this message)

Luc Pattyn7-Dec-08 1:14

7-Dec-08 1:14

Hi,

it may come as a surprise, but the order of the includes matters too.
i.e. if tchar.h relies on windows.h, then windows.h must precede tchar.h;
normally if you suddenly need another include, you put it at the end of the list.

BTW: the behavior of message editing regarding < and > depends on the checked state of "Ignore HTML tags in this message" checkbox.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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J_E_D_I7-Dec-08 19:21

7-Dec-08 19:21

Luc, you are absolutely right! I've changed the order of the include directives and it works like a breeze.
Thank you so much for this, I admit I would have never thought about it.
Smile | :)

Luc Pattyn7-Dec-08 23:06

Re: Creating Registry Key Values in C++/CLI environment

7-Dec-08 23:06

You're welcome.

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J_E_D_I13-Dec-08 7:56

Re: Creating Registry Key Values in C++/CLI environment

13-Dec-08 7:56

Hi again Luc, I was wondering if you had any hint on how to solve this problem which is somehow linked to the previous one. I need to save the value obtained with the previous code (which is a DWORD: 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?

I thank you in advance.

Luc Pattyn13-Dec-08 8:26

13-Dec-08 8:26

Hi,

there are two ways to solve this:

1.
most registry operations are supported in .NET by the Registry class
things not supported include special key types (not REG_SZ)

2.
when the Registry class does not offer what you need, you have to call the native functions (such as RegCreateKeyEx).

I don't know the details for C++, but you somehow must tell it where the library functions can be found,
and how they should be called.

This article[^] probably contains all you need and more.

FYI: in C# there is only one way to access native code, that is thru P/Invoke.

Remark: you would better have started a new thread for a question that hardly is connected to an old topic... that would have improved your chances for someone else to pick it up.

Smile | :)

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Mark Salsbery7-Dec-08 6:12

7-Dec-08 6:12

As Luc mentioned, the order of the #includes can be a factor.

Another recent post asked about tchar.h and I tested it - it can be
used all by itself and it pulls in any additional header files it needs,
so I wouldn't think that's an issue here..

In your stdafx.h file, you may be missing the Windows versioning macros.
The macros have changed a bit in recent SDK versions, but if you create a dummy
project (MFC or Win32) you can look at the stdafx.h file and see the defaults.
For example, here's a stdafx.h file from one of my projects, using the latest SDK
on VS 2008:

// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently,
// but are changed infrequently

#pragma once


#define WIN32_LEAN_AND_MEAN

#include "<code>targetver.h</code>"

#include <stdio.h>
#include <tchar.h>

#ifndef VC_EXTRALEAN
#define VC_EXTRALEAN
#endif

// Windows Header Files:
#include <windows.h>

// <code>targetver.h</code>


#pragma once


#ifndef NTDDI_VERSION
#define NTDDI_VERSION NTDDI_WINXPSP2
#endif


#ifndef WINVER
#define WINVER _WIN32_WINNT_WINXP
#endif

#ifndef _WIN32_WINNT
#define _WIN32_WINNT _WIN32_WINNT_WINXP
#endif

#ifndef _WIN32_WINDOWS
#define _WIN32_WINDOWS 0x0410
#endif

#ifndef _WIN32_IE
#define _WIN32_IE 0x0600
#endif

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

J_E_D_I7-Dec-08 19:24

7-Dec-08 19:24

Hi Mark, thanks for this detailed suggestion. Luc's advice however solved the problem easily and for the time being I'll stick with it. I'll definitely look into your solution if a similar problem happens in the future. Cheers Big Grin | :-D