pointer-to-array - C / C++ / MFC Discussion Boards

durban221-Mar-09 5:07

21-Mar-09 5:07

MFC, STUDIO 2008,
Project use UNICODE
CString m_sTest;
m_sTest = L"Байкал";
char *m_pchar3;
m_pchar3 = new char[70];
How todo m_sTest into m_pchar3?
//- m_pchar3=m_sTest; // error C2440: '=' : cannot convert from 'CString' to 'char *'
//- strcpy(m_pchar3, m_sTest); // error C2664: 'strcpy' : cannot convert parameter 2 from 'CString' to 'const char *'
//- strcpy(m_pchar3, (TCHAR)m_sTest); // error C2440: 'type cast' : cannot convert from 'CString' to 'TCHAR'
//- _tcscpy( m_pchar3, (TCHAR*)(LPCTSTR)m_sTest ); // error C2664: 'wcscpy' : cannot convert parameter 1 from 'char *' to 'wchar_t *'

Re: convert

CPallini21-Mar-09 5:13

CPallini

21-Mar-09 5:13

Why do you need to do that?
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: convert

Dominik Reichl21-Mar-09 5:14

Dominik Reichl

21-Mar-09 5:14

CHIVOTIOV wrote:
char *m_pchar3;
m_pchar3 = new char[70];

Use TCHAR instead of char.

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Re: convert

Akt_4_U21-Mar-09 5:52

Akt_4_U

21-Mar-09 5:52

The m_sTest is a UNICODE string. So if you want to convert this UNICODE string to char* use WideCharToMultiBye API or use CRT function wcstombs.

prvn

Re: convert

Eytukan21-Mar-09 22:02

Eytukan

21-Mar-09 22:02

CHIVOTIOV wrote:
/ error C2664: 'wcscpy' : cannot convert parameter 1 from 'char *' to 'wchar_t *'

Just a padding to the other replies here. As the above lines says, You are trying to squeeze a 2 Byte string (UNICODE) into a single byte string(ANSI).

char , std::string , etc by default belong to the single byte representation.
wchar_t, std::wstring, etc represent UNICODE representation.

TCHAR is "neutral" based on the scheme used, it switches type accordingly. If you define # UNICODE in the setting, the string becomes 2 byte reps. If you don't define it, it becomes single byte. Also when you use TCHARs, you should use strings apis specific to TCHARs. (like _tcscpy) that assures complete independence to your character-set implementations.

Similarly, CString switches types based on the project character-set settings.(UNICODE/Single-byte).

Now you have defined UNICODE in your project settings but trying a cross-copy operation. So just figure out what needs to be done.. Smile | :)

He never answers anyone who replies to him. I've taken to calling him a retard, which is not fair to retards everywhere.-Christian Graus

how to write list control data in text file in MFC

amit14aug21-Mar-09 4:38

amit14aug

21-Mar-09 4:38

hi,
Can Anybody tell me how to write a list control data in text file in MFC?

Re: how to write list control data in text file in MFC

Rajesh R Subramanian21-Mar-09 4:41

Rajesh R Subramanian

21-Mar-09 4:41

CListCtrl has member functions like GetItem(), GetItemData(), etc., and there's CFile that you can use to write to file. Where exactly are you stuck?

It is a crappy thing, but it's life -^ Carlo Pallini

pointer-to-array

korte2521-Mar-09 3:49

korte25

21-Mar-09 3:49

Hi!

I have an array of pointers, which point to classes derived from the same class. I also have a pointer, that points to the array. Is there a simple way to find out to which element of the array this pointer points to, or shall i use a variable in the base class for this purpose?
Thanks

Re: pointer-to-array

CPallini21-Mar-09 4:09

CPallini

21-Mar-09 4:09

You may use RTTI [^].
Smile | :)

Re: pointer-to-array

korte2521-Mar-09 6:09

korte25

21-Mar-09 6:09

Actually, this solves another problem of mine, so thanks a lot Big Grin | :-D

However, I'd like to know, whether the pointer points to the 2nd, 5th, nth element of the array. If I understand the description correctly, type_info only gives me the name of the class my pointer-in-the-array points to (right?). First I thought of using sizof(), but my derived classes are of different sizes.

Re: pointer-to-array

CPallini21-Mar-09 6:25

CPallini

21-Mar-09 6:25

Please post the relevant code (I need to know the pointer relationship with the array).
Smile | :)

Re: pointer-to-array

korte2521-Mar-09 6:57

korte25

21-Mar-09 6:57

I have a base class, let's say Car, and derived classes BMW, Mercedes, Renault, etc.
The array is: Car* p_Cars[2][16];
The pointer: Car** pCar;

for (int i = 0; i < 2; i++)
{
    for (int j = 0; j < 16; j++)
    {
        if (j==2 || j==3)
            p_Cars[i][j] = new BMW(i, j);
        else if (j==4 || j==5)
            p_Cars[i][j] = new Mercedes(i, j);
        .
                    .
                    .
    }
}

So I'd like to know, whether I can determine the element from its address.
I hope you understand my problem, i tried my best Sniff | :^)

Re: pointer-to-array

CPallini21-Mar-09 7:41

CPallini

21-Mar-09 7:41

A given value of pCar refers to the element p_Cars[i][j] (i.e. pCar == &p_Cars[i][j] holds true), provided i,j are computed as follows:

int k = (int) (pCar - &p_Cars[0][0]);
int i = k / 16;
int j = k % 16;

Re: pointer-to-array

korte2521-Mar-09 7:44

korte25

21-Mar-09 7:44

thanks

Re: pointer-to-array

CPallini21-Mar-09 7:48

CPallini

21-Mar-09 7:48

You are welcome.
Smile | :)

Re: pointer-to-array

Stuart Dootson21-Mar-09 12:29

Stuart Dootson

21-Mar-09 12:29

So....you have:

CBase* pArray[] = { whatever... };
CBase* pItem = address_of_some_item_in_the_array;

?

In that case:

const size_t index = pItem - pArray;

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: pointer-to-array

korte2522-Mar-09 2:30

korte25

22-Mar-09 2:30

thx

CreateDirectoryW()

p_196021-Mar-09 3:47

p_1960

21-Mar-09 3:47

Hi,
May i know how to check if a folder or file exists and if not create a folder....

im using ...
CString csPath1="C:\\Temp\\myfolder";

if(_access (csPath1+_T("\\Test"), 0)==-1);
::CreateDirectoryW(csPath1+L"\\Test",NULL);

and im getting the below error....
'_access' :cannot convert parameter 1 from 'ATL::CStringT<BaseType,StringTraits>' to 'const char *'...

Please help me......(myproject is in unicode)

Re: CreateDirectoryW()

«_Superman_»21-Mar-09 4:05

«_Superman_»

21-Mar-09 4:05

Why do you need to check first?
CreateDirectory will return ERROR_ALREADY_EXISTS if the directory already exists.

«_Superman_»
I love work. It gives me something to do between weekends.

Re: CreateDirectoryW()

p_196021-Mar-09 4:17

p_1960

21-Mar-09 4:17

Thanks for ur help and please let me know how can i check whether a file(not directory) exists....(my project is in unicode)........

Re: CreateDirectoryW()

Rajesh R Subramanian21-Mar-09 4:28

Rajesh R Subramanian

21-Mar-09 4:28

You can use PathFileExists()[^] function (works with both folders and files).

The page contains a sample as well - saves me from typing code. Do remember to include shlwapi.h and link to shlwapi.lib.

It is a crappy thing, but it's life -^ Carlo Pallini

How to use Borland C DLL in C#.NET

dataminers21-Mar-09 3:28

dataminers

21-Mar-09 3:28

How can I use DLL file in C#.NET ? I create dll in Borland C++ Compiler 5.5.1 and using C language.

Following code is not work.

My C Code;
-----------------------------------------------------
//hello.dll
#include <windows.h>

extern "C"
{
void __declspec (dllexport) function1()
{

MessageBox (NULL, "test message","test title",0);
}
}

BOOL WINAPI DllMain (HINSTANCE, DWORD, LPVOID)
{
return TRUE;
}

My C# Code;
-----------------------------------------------------

[DllImport("C:\hello.dll")]
public static extern void function1();

private void button1_Click(object sender, EventArgs e)
{
function1();
}

Re: How to use Borland C DLL in C#.NET

dataminers21-Mar-09 3:49

dataminers

21-Mar-09 3:49

Ok, I try this; But I get this error: Entry Point Not Found

C DLL CODE
-----------------------------------------------

#include <windows.h>

BOOL __stdcall DllMain(HINSTANCE hInst, DWORD dwReason, LPVOID lpReserved) {
return TRUE;
}

__declspec(dllexport) void __stdcall Message(char* p_szMessage) {
MessageBox(NULL, p_szMessage, "Message from DLL", MB_OK);
}

C# DLL CODE
-----------------------------------------------

[DllImport("filename.dll")]
static extern void Message(string msg);

private void button1_Click(object sender, EventArgs e)
{
Message("Hello world");
}

Re: How to use Borland C DLL in C#.NET

CPallini21-Mar-09 4:03

CPallini

21-Mar-09 4:03

What does it mean, specifically, 'it doesn't work' (i.e. more details needed)?

BTW you possibly would get better help at C# forum.

BTW2: I saw you've already cross-posted your question... Roll eyes | :rolleyes:

Re: How to use Borland C DLL in C#.NET

dataminers21-Mar-09 5:04

dataminers

21-Mar-09 5:04

cross-posted is forbidden? Because this question related about between c and c#.

How can I "dumpbin -exports dll" in borland c++ 5.5.1 compiler on command prompt?

Do you have any idea?

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