C / C++ / MFC

19-Dec-05 20:47

Hi,

I created template class just like:
template < typename T > class DataList
{
AddNode(const T val) // Input data must be read only
{
// some codes
}
// some more functions
};

In main():

LPCSTR str = "Hello"; // Const char string
DataList<char*> data; // Data list for char strings
data.AddNode(str); // Add the string

When compiling I get the error as...
error C2664: 'AddNode' : cannot convert parameter 1 from 'const char *' to 'char *const '

What could be wrong?

Thank you.

<B>- NS -</B>

vikas amin19-Dec-05 23:24

19-Dec-05 23:24

What do u actully want to do with
this type of declaration.
Can u tell me reason so that i can
help u to find some solution .
Cool | :cool:

Vikas Amin
Embin Technology
Bombay
vikas.amin@embin.com

Nishad S20-Dec-05 0:01

20-Dec-05 0:01

I am creating a general purpose linked list class.

It is basically used for numbers. In that case no problem.

I intended to use it for strings also. In that case the AddNode function is supposed to accept 'const char*' as input. In the template class I wrote some virtual functions that can be used for allocating memory for the strings, in the derived classe.

For example, in AddNode I will call a function like
virtual void SetVal(...);
In the base class, this function just copies the input value to the node value. But in the derived class, it will allocate memory needed for storing the input string to node value and copy the string using strcpy(...).

I think, you got what I want to do. I won doing this by excluding the const input string. But it is recommented that pass input strings as read only.

- NS -

vikas amin20-Dec-05 0:19

20-Dec-05 0:19

<br />
template < typename   T > class DataList<br />
{<br />
 public:<br />
AddNode(const T val) // Input data must be read only<br />
{<br />
  // some codes<br />
  // val="v";<br />
}<br />
  // some more functions<br />
};<br />
<br />
<br />
IN Main function <br />
<br />
LPCSTR str = "Hello";  // Const char string<br />
DataList< char *> data; // Data list for char strings<br />
data.AddNode((char*)str);     // Add the string<br />

the above code satisfies your demand , i just type casted the LPCSTR to char *
and to access the AddNode declared it with Public scope .
If u want to check just try changing the { val="v";} u will see an compiler
error for constant.

//////////////////////////////////////////////////////////////////////

Cool | :cool:

Vikas Amin
Embin Technology
Bombay
vikas.amin@embin.com

Nishad S20-Dec-05 0:29

20-Dec-05 0:29

I'm sorry, it will make every call to this function need a typecast, which is not acceptable...

Further more the input data is not sefe.

You wrote:
val="v";

In this, the pointer, val is become a const, that's why we cannot assign another pointer("v") to it. But we can change the contents, for example *val = 'a' or strcpy(val,"hi") is possible.

- NS -

vikas amin20-Dec-05 1:31

20-Dec-05 1:31

template < typename   T > class DataList<br />
{<br />
public:<br />
AddNode(const T val)  // Input data must be read only<br />
{<br />
  // some codes<br />
*val='a';<br />
}<br />
// some more functions<br />
};<br />
<br />
<br />
In Main function <br />
<br />
LPCSTR str = "Hello";  // Const char string<br />
DataList<const char *> data; // Data list for char strings<br />
data.AddNode(str);   <br />

Now in this code there is not type casting and also
the *val='a' ; condtion is satisfied .

Cool | :cool:

Vikas Amin
Embin Technology
Bombay
vikas.amin@embin.com

Nishad S20-Dec-05 1:43

20-Dec-05 1:43

I'm afraid that you forgot my problem. Actually our discussion reached exactly at where we start from.
Could you please read it agian?

- NS -

Zdeslav Vojkovic20-Dec-05 0:05

Zdeslav Vojkovic

20-Dec-05 0:05

replace LPCSTR with LPSTR.

you instantiate a DataList specialization on char* parameter, but you send incorrect parameter type to AddNode().

AddNode expect constant instance of type T (therefore, constant pointer to char, or char* const),
but you send a pointer to constant char (const char*).

although the syntax looks similar, semantics is quite different. please look it up in language reference.

hope this helps

-- modified at 6:06 Tuesday 20th December, 2005
of course, be aware that literal strings can't really be modified because they are placed in protected part of memory (executable image), so if you write

LPSTR str = "Hello"; // Const char string       <br />
str[1] = 'a';

you will get an access violation.

-- modified at 6:15 Tuesday 20th December, 2005

How to include dlls in VC++.NET application.

khan++20-Dec-05 0:31

khan++

20-Dec-05 0:31

I think its because you are declaring:
DataList<char*> data;
And then using LPCSTR with it.

A char* is a pointer to a list of characters, terminated by NULL, while LPCSTR's declaration is:
typedef CONST CHAR *LPCSTR, *PCSTR;

I think changing DataList<char*> data; to DataList<LPCSTR> data; etc should solve the problem.

this is this.

snprani19-Dec-05 20:34

snprani

19-Dec-05 20:34

Hi to all,

I am having more than 20 dlls for my application. if i want to store those dlls in one folder and use them while running the application what i have to do?

For example all header files if I copy in one folder and giving this folder name in include folders of Tools->Options then it works fine. Is there any method like this for Dlls. Please help me.

Thanks in advance.

saving locations of ActiveX in application

Sac87Rak19-Dec-05 20:23

Sac87Rak

19-Dec-05 20:23

ActiveX Controls Test Container saves file as .tcs. If Activex Control is placed anywhere in container and save it and next time if we open that .tcs file activex controls are placed on same locations as it was at the time of saving in .tcs file. I want to implement this functionality (drag & Drop of activex controls in application)in my project. so how should i do this or if any other solution is there for this problem or if anybody could give me file format of this .tcs file of ActiveX Controls Test Container.

Getting Problem when using NetMeeting SDK

trinadh_t19-Dec-05 20:09

trinadh_t

19-Dec-05 20:09

Hi,

This is Trinadh. I am VC++ developer in AxSys HealthTech Ltd. Now there is a requirement in my company is to Use PlugTransport.exe (Micrsoft NetMeeting SDK Sample) within Service. When i am trying to use PlugTransport.exe in Service, i am getting problem at hr = m_pINmMgr->Initialize(&uOptions,&uCaps); in nmsession.cpp statement. The problem is i am unable to get SUCCESS or FAILURE of hr even i am using winerror.h in PlugTransport.dsw. This Method unable to return any value when i am using PlugTransport.exe within service.

With this problem i am unable to stop Service and PlugTransport.exe, conf.exe are unable to delete from TaskManager and those are becoming Access Denied.
Now there is urgent requirement in my company to use PlugTransport.exe with in service.

Kindly let me know the reason for this. I am waiting for your fast response.

Regards
Trinadh

Need help

coolsab19-Dec-05 20:09

coolsab

19-Dec-05 20:09

Hi
i am a newbie to VC++ . I do have a requirment ..but i dont how to start that ..
My requirment is my program need to send a message to client program whenever a window flashes in my desktop ( for example if any new message comes from Yahoo messenger my program need to capture that .. ). Its a bit urgent .Pls help me

Re: Need help

ThatsAlok19-Dec-05 21:33

ThatsAlok

19-Dec-05 21:33

coolsab wrote:
My requirment is my program need to send a message to client program whenever a window flashes in my desktop ( for example if any new message comes from Yahoo messenger my program need to capture that .. ).

Set System wide Hook for WM_CREATE, WM_SHOWWINDOW for Yahoo Messenger popup window... here in the article will help you to achieve same :-
http://www.codeproject.com/system/hooksys.asp[^]

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Re: Need help

vikas amin19-Dec-05 22:59

About termintaing System processes..

19-Dec-05 22:59

Check out the windows hook fundamentals
that can help u ?
but if there are some spyware prevension
software installed hooks might not work
properly.
ok
Cool | :cool:

Vikas Amin
Embin Technology
Bombay
vikas.amin@embin.com

index server catalogs

akshayswaroop19-Dec-05 19:33

akshayswaroop

19-Dec-05 19:33

is it possible to read index server catalogs??
pls help its urgent

Supriya Tonape19-Dec-05 19:30

Supriya Tonape

19-Dec-05 19:30

Hi,
We can not kill the system processes (eg. System, Services.exe etc) trhu Terminateproc API, am I right??? Also for System processes we dont get handle when we try to get it from 'openprocess' API...
do let me know..
Thanks
Supriya Tonape

kakan19-Dec-05 21:19

kakan

19-Dec-05 21:19

Why don't you just shutdown Windows, instead of try to kill it's vital processes? Confused | :confused:

Supriya Tonape20-Dec-05 21:56

Supriya Tonape

20-Dec-05 21:56

I wanted to terminate the process thru my appln, so cant shutdown windows Smile | :)

seems, didnt get my prob, by Ur way after restarting PC again those SYSTEM processes wud get started...hope U got that Smile | :)

thanks
Supriya Tonape

ThatsAlok19-Dec-05 21:26

ThatsAlok

19-Dec-05 21:26

Supriya Tonape wrote:
We can not kill the system processes (eg. System, Services.exe etc) trhu Terminateproc API, am I right??? Also for System processes we dont get handle when we try to get it from 'openprocess' API...

Yeah you can kill the these process, but for killing that process you should be havinf SYSTEM priviledge.. Only services running in your computer can run on this priviledge.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Supriya Tonape20-Dec-05 22:03

Supriya Tonape

20-Dec-05 22:03

Thanks Alok, Even if U have those privileges(me not very sure abt this privileges) U cant kill SYSTEM processes since they are necessary n if U will kill it manually from TASK Manager Ur PC wud get rebooted.
But anyways, I got the solution, like GetLastError() returns me "E_ACCESSDENIED" error and thats OK wid my appln Smile | :)

thanks
Supriya Tonape

ThatsAlok20-Dec-05 22:25

ThatsAlok

20-Dec-05 22:25

Supriya Tonape wrote:
Even if U have those privileges(me not very sure abt this privileges) U cant kill SYSTEM processes since they are necessary

Yeap you can kill them... because I myself have done that.....

Supriya Tonape wrote:
since they are necessary n if U will kill it manually from TASK Manager Ur PC wud get rebooted.

When i killed that application ... My system get unstable, not rebooted and after some time as precaution measure Windows have restarted these process with new PID.

check this site.. i hope it still working http://www.securenm.com that application is using similiar concept

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV