C / C++ / MFC

Re: help needed::win32 error 10106

31-May-02 23:47

As the error text informs you, this is an error from the XTG component (the ODBC driver?). If you indeed were a "software engineer" you'd know that an error 10106 is a Winsock error (WSAEPROVIDERFAILEDINIT). Perhaps the ODBC DSN is wrong?

l a u r e n1-Jun-02 2:30

l a u r e n

1-Jun-02 2:30

Mike Nordell wrote:
If you indeed were a "software engineer" you'd know that an error 10106 is a Winsock error

ooooooo harsh
OMG | :OMG:

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help needed::win32 error 10106

ash250931-May-02 22:15

ash2509

31-May-02 22:15

char* template parameter [edited]

Paul M Watt31-May-02 21:55

31-May-02 21:55

Does any one know how if it is possible, and how to derive from a templatized class that specializes with a specific text string. Here is an example:

template<char* str>
class X
{
void print()
{
cout << "Your initialized Template string is: " << str << endl;
}
};

class Y : public X<"display">
{
...
};

//then instantiate and use the class like so:
Y yDisplay<"display">;
yDisplay.print();

// and here is the output
Your initialized Template string is: display

I can perform this feat with a DWORD. And I can instantiate an X type object that specializes on a text string.

//This seems to work fine.
X xObject<"hello">;

But I cannot figure out if it is possible to derive from a class that has specialized on a particular text string as a template parameter.

Thanks in advance.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Michael Dunn31-May-02 22:16

Michael Dunn

31-May-02 22:16

Answer here.

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Paul M Watt31-May-02 22:39

31-May-02 22:39

Thank you for the link, it has a lot of good information. However my problem is a little more difficult than that. I actually stumbled on the solution to get the string literal to work, however I still have the problem of deriving a class from a templatized class that contains a specific string literal.

Example:

Does any one know how if it is possible, and how to derive from a templatized class that specializes with a specific text string. Here is an example:

template<char* str>
class X
{
};

//Notice how this class is derived from a specialized version of X with a specific string literal.
char DISPLAY_STR[] = "display";
class Y : public X<DISPLAY_STR>
{
...
};

THis is the error that I receive as well.
'X' : template argument 'str' : invalid address of local variable 'str'

Thanks again

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Mike Nordell31-May-02 23:52

31-May-02 23:52

kilowatt wrote:
//Notice how this class is derived from a specialized version of X with a specific string literal.
char DISPLAY_STR[] = "display";
class Y : public X<DISPLAY_STR>

This is no string literal. "foo" is a string literal. You're trying to use a variable and that will (of course) fail miserably.

If your intention is to "hide" the real string used as a literal behind another name, your only option is to use a macro:
#define DISPLAY_STR "display"

Paul M Watt1-Jun-02 5:09

1-Jun-02 5:09

Well, you have a point with my misuse of vocabulary on the problem.

However if I want to instnatiate class X with a string parameter, the method that you have suggested will not work. If you read the link that Mike Dunn posted above, you need to create a variable with external linkage in order for the template to be able to use it. Here is a summary.

#define FOO_DEFINE "foo"

X xObject1<"foo">; //will not work
X xObject2<foo_define> //will not work either, same as xObject<"foo">

char FOO_STR[] = "foo";
X xObject3<foo_str>; //THe correct way to do it.

Anyway my real problem is that I want to derive a class Y from a specialized version of X, like so:

class Y : public X<foo_str>
{

};

class Y is not a parameterized class, however it will use a special version of X.

Thanks again.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Joaquín M López Muñoz1-Jun-02 4:33

Joaquín M López Muñoz

1-Jun-02 4:33

The error message is descriptive enough. What is the linkage of DISPLAY_STR? It has to be external for the template to work. The problem has nothing to do with deriving from X<DISPLAY_STR>: you should meet it also by simply instantiating a X<DISPLAY_STR>.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Paul M Watt1-Jun-02 5:53

1-Jun-02 5:53

I typed up a simple version like the example that I showed you guys and got it to work, then I found tha tI had declared <const char*> instead of <char*> as the template parameter and now it works.

Thanks

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Paul M Watt1-Jun-02 5:56

export template class in DLL

1-Jun-02 5:56

I now know that it is possible and here is how it can be done:

#include "stdafx.h"
#include <iostream>
using std::cout;

char szHello[] = "Hello ";
char szWorld[] = "World!";

template<char* str>
class X
{
public:
	void print() 
	{
		cout << str;
	}
};

class Y : public X<szWorld>
{
public:
	int i;

	Y();
};


Y::Y () : X<szWorld>()
{
	
};


int main(int argc, char* argv[])
{
	X<szHello> xObject;
	xObject.print();

	Y yObject;
	yObject.print();


	return 0;
}

Thanks for all of your help.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

How to use checkbox?

31-May-02 18:05

I want to use the checkbox like this:
if(checkbox was clicked)
{}
else{}
how could I do ?

Re: How to use checkbox?

Ravi Bhavnani31-May-02 18:39

Ravi Bhavnani

31-May-02 18:39

if (IsDlgButtonChecked (IDC_CHECKBOX)) {
  // do something...
} else {
  // do something else...
}

/ravi

Help put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Re: How to use checkbox?

Eugene Pustovoyt31-May-02 21:05

Eugene Pustovoyt

31-May-02 21:05

Try this:

CButton * pButton = (CButton*)GetDlgItem(IDC_CHECK1);
if (pButton->GetCheck())
{
}
else
{
}

Best regards,
Eugene Pustovoyt

31-May-02 18:02

Can anyone tell me how can I export template class from a DLL.

I have created a wrapper to wrap some STL containers (as STL can't export through DLL boundary), and wanna export the wrapper as accessor.

Say, I declared in "ListType.h"

<br />
#ifdef DLL_EXP<br />
  #define MY_EXP __declspec(dllexport)<br />
#else<br />
  #define MY_EXP __declspec(dllimport)<br />
#define<br />
<br />
template class MY_EXP CMapList<T><br />
{<br />
   void insert(long key, T* pd)<br />
   {<br />
     ....<br />
   }<br />
   bool next() { .... }<br />
   T* get() { .... }<br />
<br />
   ....<br />
};<br />
<br />
class CMyClass1;<br />
class CMyClass2;<br />
<br />
CMapList<CMyClass1>;<br />
CMapList<CMyClass2>;<br />

I tried to use the wrapper class in the App project, but I experienced Access Violation with subsequence next() and get() calls.

How can I make sure the DLL project is exporting the class CMapList<cmyclass1> and CMapList<cmyclass2> ?

How can I avoid that the App project will use the declaration in the DLL, not generated CMapList<cmyclass1>, CMapList<cmyclass2> from the header file directly ?

Thanks for help ^^

31-May-02 18:10

Sorry, the code section before should be :

<br />
#ifdef DLL_EXP<br />
#define MY_EXP __declspec(dllexport)<br />
#else<br />
#define MY_EXP __declspec(dllimport)<br />
#define<br />
<br />
template class MY_EXP CMapList<T><br />
{<br />
void insert(long key, T* pd)<br />
{<br />
....<br />
}<br />
bool next() { .... }<br />
T* get() { .... }<br />
<br />
....<br />
};<br />
<br />
class CMyClass1;<br />
class CMyClass2;<br />
<br />
CMapList<CMyClass1><br />
CMapList<CMyClass2><br />

Mike Nordell31-May-02 23:56

31-May-02 23:56

Can anyone tell me how can I export template class from a DLL.

Yes. Use Comeau C/C++ compiler. That is currently the only publicly available compiler that can make use of the export keyword.

The best you can do with MSVC is to export a specialization or provide a non-data-type-dependent implementation of something in/from the DLL and then create your class templates as thin wrappers around what the DLL exports.

1-Jun-02 5:28

But I have to tie to MSVC++ 6.0. I'm doing a wrapper to wrap the dependence of STL within the DLL. However, I don't know how to put the class template CMapList<cmyclass1> specification into the DLL. If I just put the template CMapList<cmyclass1> into the header file. Will it generate code to put into the DLL ? ( I don't think so )

Mike Nordell1-Jun-02 7:28