C / C++ / MFC

Detecting internet connection using InternetGetConnectedState in VC++

13-Dec-07 17:15

Hi all,

I have two applications, console application with MFC support and MFC DLL application. I want to connect both those two application together. Console application gives the required data to DLL.

So how should I do it.

I appreciate your help all the time...
Eranga Smile | :)

Kogee San13-Dec-07 16:58

Kogee San

13-Dec-07 16:58

Hello again everyone

Before that i would like to tell u all that im really new and dumb to .NET. Hope you guys can help me. I tried to search the solution to my problem but still couldnt find anything.

What im trying to do is to create a really simple internet connection detection which is running under a win32 console. The program will detect if there is any connection to the internet, if yes then it will print yes. If no connection then it will print out no connection using printf() statement.

I know that the InternetGetConnectedState API can help me. but still im not so sure on how to use it. Really dumb me...the scenario is like this

I already link the VC++ project to the Wininet.lib since it required that lib and a header file called Wininet.h (as refered in MSDN). I try to code just by adding the header file to the source code

<br />
#include "stdio.h"<br />
#include "Wininet.h"<br />
void main()<br />
{<br />
}<br />

using the code above, compile, it generates more than 100 error which particularly made the compiler to stop compiling due to error exceeds 100. all of the errors come from the Wininet.h header file. The first error was "error C2061: syntax error:Identifier 'HINTERNET'. The question is, am i missing something. Does VC++ supports this API? I've search the internet (forums..etc) and all of them were implemented using C# or VB. Is there any source code samples using this API which can be run only in a simple win32 console application? Thank you everyone. Really appreciate any help. Thanks again.

Re: Detecting internet connection using InternetGetConnectedState in VC++[Modified]

Naveen13-Dec-07 17:11

Naveen

13-Dec-07 17:11

Kogee San wrote:
it generates more than 100 error which particularly made the compiler to stop compiling due to error exceeds 100. all of the errors come from the Wininet.h header file.

modify ur code as follows

#include "stdio.h"
#include <windows.h>
#include "Wininet.h"
void main()
{
}

nave

[OpenedFileFinder]

Re: Detecting internet connection using InternetGetConnectedState in VC++[Modified]

Kogee San13-Dec-07 17:19

Kogee San

13-Dec-07 17:19

wow. It really works. Thanks. Just wanna ask if you dont mind. Why do we need to add windows.h. I always see codes which add windows.h eventhough it is just a hello world printf statement. Just kinda curious. Thanks again.

Re: Detecting internet connection using InternetGetConnectedState in VC++[Modified]

Naveen13-Dec-07 18:34

Naveen

13-Dec-07 18:34

Kogee San wrote:
Why do we need to add windows.h.

This is because the Wininet.h file use some other data types such as LPVOID. This is defined in some other header files. For getting the definition of such items we need to include the windows.h

nave

[OpenedFileFinder]

Re: Detecting internet connection using InternetGetConnectedState in VC++[Modified]

David Crow14-Dec-07 3:40

David Crow

14-Dec-07 3:40

Kogee San wrote:
I always see codes which add windows.h eventhough it is just a hello world printf statement.

Then those programs included it unnecessarily.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: Detecting internet connection using InternetGetConnectedState in VC++[Modified]

Kogee San16-Dec-07 14:28

Kogee San

16-Dec-07 14:28

Thanks guys for your help and comments. Really appreciate it.

Template

james_dixon_200813-Dec-07 15:23

james_dixon_2008

13-Dec-07 15:23

Hello developers,

Can i define a class in header file and declare it in .cpp file if using template or do i have to define and declare in the same header file. I have got two classes so do i have to define and declare both in the same header file or is it possible to have different header file for both classes.

I am writing double linked list application. Now i have got two class LList and Node. Now when i simply use template and write the two classes under one file without defining it , then it works perfectly fine but when i try to define the two class seperately i am getting many errors. What should i do in this case ?

Any way out ?

ThankYou

Mark Salsbery13-Dec-07 16:26

13-Dec-07 16:26

When you split the two classes into two header files, did
you remember to #include the dependent header file in the one
that depends on it?

If these are template classes, there shouldn't be any code in
CPP files. Actual intances of the template class aren't created
until an object of the class is defined, so at that point the compiler
would need to see the code in the CPP file.

Mark

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

james_dixon_200813-Dec-07 17:19

james_dixon_2008

13-Dec-07 17:19

Thanks,
yes i included the dependent header file but i got many errors. But when include the node class declaration and defintion and llist class declartion in one header file then the program works. But yes if i try to declare the llist class first and then define it, it gives me many error.

So i came to the conclusion that i have included all the code under one header file. Declaring template node class and then defining all the functions and then directly defining the template llist class as it doesn't work when i first declare it and then define it.

I guess that each template class could be placed in different header file to use by main method. But in my case it's not working. So i have only main class and the one header file containing two template class.

Mark Salsbery13-Dec-07 18:50

13-Dec-07 18:50

If the list class references the node class then the node
class will always have to be defined before (in compile order)
the list class, whether you use separate header files or not.

The following is no different than using a single header file for
both classes...

/////////////////
// node.h

#pragma once

...define node class...


/////////////////
// list.h

#pragma once

#include "node.h"

...define list class...


////////////////
// any file that uses the list class

#pragma once

#include "list.h"
...

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

Check for input from console in C++

Nibu babu thomas13-Dec-07 16:32

Nibu babu thomas

13-Dec-07 16:32

james_dixon_2008 wrote:
Can i define a class in header file and declare it in .cpp file if using template

Read this -> http://www.parashift.com/c++-faq-lite/templates.html#faq-35.12[^]

Nibu thomas
Microsoft MVP for VC++

Code must be written to be read, not by the compiler, but by another human being.

Programming Blog: http:\\nibuthomas.wordpress.com

dabs13-Dec-07 14:45

dabs

13-Dec-07 14:45

Hi,

I have a loop in a C++ program which is constantly checking for input from a network source, but I also want to check if the user has entered something into the console - such as a command to stop the program. Obviously I cannot use just standard cin << strCommand;, since that would block until something is entered. Is there any way for me to check if the console has received input?

Regards,
Daníel

Wenn ist das Nunstück git und Slotermeyer? Ja! Beierhund das oder die Flipperwaldt gersput!

Re: Check for input from console in C++

Naveen13-Dec-07 16:12

Naveen

13-Dec-07 16:12

you can use the _kbhit() function. This function returns a nonzero value if a key has been pressed.

Re: Check for input from console in C++

dabs14-Dec-07 3:28

dabs

14-Dec-07 3:28

Thanks, exactly what I need!

Regards,
Daníel

Wenn ist das Nunstück git und Slotermeyer? Ja! Beierhund das oder die Flipperwaldt gersput!

CString into string

CodingLover13-Dec-07 14:27

13-Dec-07 14:27

Hi all,

What is the easiest way to convert a CString into a standard C++ sting.

Thanks

I appreciate your help all the time...
Eranga Smile | :)

Re: CString into string

Mark Salsbery13-Dec-07 15:16

13-Dec-07 15:16

Eranga Thennakoon wrote:
...a standard C++ sting

An array of characters?

CString CStr = ...;
LPTSTR pTCharStr = new TCHAR[CStr.GetLength() + 1];
_tcscpy_s(pTCharStr, CStr.GetLength() + 1, CStr);

Or an STL string?

    #include <string>
...
    CString CStr = ...;
#if defined(_UNICODE)
    wstring stdstr = CStr;
#else
    string stdstr = CStr;
#endif

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

Re: CString into string

CodingLover13-Dec-07 15:34

Re: CString into string [modified]

13-Dec-07 15:34

How about this way,

std::string strRTF(ss.GetString());

ss is the CString.

But, when I use

cout << strRTF;

I got the following compiled error.

binary '<<' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion)

What can be the issue.

I appreciate your help all the time...
Eranga Smile | :)

Mark Salsbery13-Dec-07 16:19

13-Dec-07 16:19

Eranga Thennakoon wrote:
How about this way,

std::string strRTF(ss.GetString());

That's fine - what does GetString() return? If it's a CString, then
the only thing I don't like is CString is a generic (template) type
and std::string is not. The code won't be portable to Unicode builds.
This is maybe better in that case...

typedef std::basic_string<tchar> tstring;
...
tstring strRTF(ss.GetString());

Eranga Thennakoon wrote:
But, when I use

cout << strRTF;

How about:

cout << strRTF.c_str();

Mark

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

modified on Thursday, December 13, 2007 10:35:25 PM

Re: CString into string

CodingLover13-Dec-07 17:02

13-Dec-07 17:02

Mark Salsbery wrote:
what does GetString() return?

It return a string, standard string.

Mark Salsbery wrote:
c_str()

You are right, I have to null-terminated the string.

I appreciate your help all the time...
Eranga Smile | :)

ReadFile() hang

MMM Computers13-Dec-07 12:40

MMM Computers

13-Dec-07 12:40

I have two applications running on one computer. The first app imports data from elsewhere, parses it, and writes out several files using CreateFile and WriteFile to a directory. The second app reads each of these files from the first app using FindFirstFile, CreateFile and ReadFile, and does further processing.

The data written to these files is fairly big in each case (~8 MB), so each file write can take 2-3 seconds. Also, each batch of files can potentially be large (say 100 or more). So, while the first app is busy writing each file, the second app should be able to take the first file it finds (via FindFirstFile), and open and read it. The problem is, ReadFile doesn't return for that first file until the first app has written out ALL of its files. So this ReadFile call in essence hangs for a few minutes, possibly causing havoc elsewhere in the app.

I'm closing my file handles properly in the first app (at least I think I am), so there shouldn't be any reason for ReadFile to wait on file writes that are on different files in the same directory. Is there some "feature" in the Win32 file API that would explain this behavior? I'm writing the files using FILE_FLAG_SEQUENTIAL_SCAN and sharing disabled, if it matters; I've also played with FILE_FLAG_NO_BUFFERING to attempt to improve performance.

Re: ReadFile() hang

Mark Salsbery13-Dec-07 13:00