C / C++ / MFC

converting from const char [] to 'LPWSTR'

31-May-07 10:06

I guess this is a pretty well trodden route.

First port your VC6 C++ to VC8. The project will auto convert but you still need to tidy up all the Safe CRT change consequences to get rid of W4 Warnings. Make sure it all works with the new MFC/ATL etc.

Second if the substance of your C++ is not in COM objects, you may be in a deal of trouble. Fortunately it's not usually hard to start chunking your C++ into COM objects, depending on how big it is.

Third, once you've got the code you want to use in one or more C++ COM objects take a look at articles on C# COM Interop. It works really well once you get over the inital strangeness, doesn't require you to write a lot of code or even any PInvokes or proxy/stub nastiness.

Step four is probably to move this post to the C# Managed and mixed development forum before somebody moans;)

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: VC++ 6 -warpper

C^hris L^osinger31-May-07 10:43

C^hris L^osinger

31-May-07 10:43

if you can put your code in a C-interfaced DLL, you can use it from C# (or any language, really) without too much hassle.

image processing toolkits | batch image processing | blogging

Re: VC++ 6 -warpper

Hamid_RT31-May-07 18:27

Hamid_RT

31-May-07 18:27

I agree with Chris Losinger Dll is a good choice.

WhiteSky

maizhiming31-May-07 9:28

maizhiming

31-May-07 9:28

When I compile this code in MSVC++ 2005 express I get the following error.

SERVICE_TABLE_ENTRY DispatchTable[]=
{{"Service1",serviceMain},{NULL,NULL}};

error C2440: 'initializing' : cannot convert from 'const char [9]' to 'LPWSTR'

Pretty much where ever I am using a string I get the same error. Why doesn't the code work?

Re: converting from const char [] to 'LPWSTR'

Matthew Faithfull31-May-07 9:43

Re: converting from const char [] to 'LPWSTR'

31-May-07 9:43

I would have to see the definition of SERVICE_TABLE_ENTRY to be sure but I suspect it's defined to contain a wide character (UNICODE) string whereas "Service1" is a constant narrow character or (ASCII) string. UNICODE strings, usually, have 16bits per character while ASCII characters have only 8bits each so conversion between the two is non trivial. There's a whole world of pain involved here, code pages, locales, W2A macros, multi-byte character sets, UTF-8 and then some but what you need to do to make the above code work is make use of the _T() macro Microsoft so kindly supply.

SERVICE_TABLE_ENTRY DispatchTable[]=<br />
{{ _T( "Service1" ) , serviceMain }, {NULL, NULL}};

Enjoy.

Nothing is exactly what it seems but everything with seems can be unpicked.

Xing Chen31-May-07 15:18

Xing Chen

31-May-07 15:18

Add L before "", it declare it as wide char.

<br />
SERVICE_TABLE_ENTRY DispatchTable[]=<br />
{{L"Service1",serviceMain},{NULL,NULL}};<br />

Best Regards.

GetDIBits() function call fails

TheDelChop31-May-07 8:50

TheDelChop

31-May-07 8:50

Anybody see what the problem is with this code? GetDIBits fails, and when I call GetLastError(), it tells me that Windows "ERROR_FILE_NOT_FOUND".

<br />
<br />
GetClientRect(hDlg, &rc); // Get the rectangle dimensions of the Dialog Box<br />
      <br />
      hdc = GetDC(hDlg);  // Get a handle to the Drawing Context of the Dialog Box<br />
<br />
      rc.bottom -= (GetSystemMetrics(SM_CYHSCROLL)+GetSystemMetrics(SM_CYEDGE));<br />
      <br />
      hSavedXYContext = CreateCompatibleDC(hdc);  // Create a drawing context that is compatiable to <br />
                                                  // the drawing context on the screen<br />
      hSavedXYBitmap = CreateCompatibleBitmap(hdc, rc.right-rc.left,rc.bottom-rc.top);  <br />
<br />
      hTheDCsOriginalBitmap = (HBITMAP)SelectObject(hSavedXYContext, hSavedXYBitmap); <br />
<br />
      BitBlt(hSavedXYContext,0,0,rc.right-rc.left, rc.bottom-rc.top,hdc,0,0,SRCCOPY);<br />
      <br />
      hSavedXYBitmap = (HBITMAP)SelectObject(hSavedXYContext, hTheDCsOriginalBitmap);   <br />
<br />
<br />
      // As far as I can tell above code does exactly what it should.  It grabs a handle to the drawing<br />
      // context, along with the rectangular coordinates of the drawing context.  Then after creating<br />
      // a compatible bitmap, and selecting it into the saved drawing context, before blting it in.  <br />
<br />
<br />
      // Now we have the DC saved to hSavedContext, so we need to take it and create a <br />
      // bitmap file that we can open in Paint.  <br />
      // This involves creating a bmp structure then writing it to a file.<br />
      <br />
      GetObject(hSavedXYBitmap,sizeof(BITMAP),(LPSTR)(&bmp));<br />
      <br />
      cClrBits = (WORD)(bmp.bmPlanes*bmp.bmBitsPixel);<br />
      <br />
      cClrBits = 4;<br />
<br />
      pbmi = (PBITMAPINFO) LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER));<br />
      <br />
      // Initialize the fields in the BITMAPINFO structure.<br />
<br />
      pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);<br />
      pbmi->bmiHeader.biWidth = bmp.bmWidth;<br />
      pbmi->bmiHeader.biHeight = bmp.bmHeight;<br />
      pbmi->bmiHeader.biPlanes = bmp.bmPlanes;<br />
      pbmi->bmiHeader.biBitCount =4;<br />
<br />
      pbmi->bmiHeader.biCompression = BI_RGB;<br />
<br />
      pbmi->bmiHeader.biSizeImage = (pbmi->bmiHeader.biWidth + 15)/16 <br />
                                      * pbmi->bmiHeader.biHeight * 4;<br />
<br />
      pbmi->bmiHeader.biClrImportant = 0;<br />
          <br />
      // Make sure to fill in the rest of the BITMAP info in the header.<br />
<br />
      pBitmapInfoHeader = (PBITMAPINFOHEADER)pbmi;<br />
<br />
      lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED,pbmi->bmiHeader.biSizeImage);<br />
           <br />
      test = GetDIBits(hdc,hSavedXYBitmap,0,(WORD) pbmi->bmiHeader.biHeight,<br />
                lpBits,pbmi,DIB_RGB_COLORS);<br />
<br />
      test = GetLastError();<br />

I would appreciate any feedback, as I am out of ideas.

Re: GetDIBits() function call fails

John R. Shaw31-May-07 9:17

John R. Shaw

31-May-07 9:17

You have to check all the values passed to GetDIBits very carefully. That functions is very touchy and will fail if a single bit is not correct. I do not think the error message has anything to do with the code you are showing, as GeDIBits will often fail without generating any error at all.

See CDibData[^], it might help.

Note: CDibData has a minor bug that I still have not updated, but it has been a while since I played with graphics.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: GetDIBits() function call fails

Mark Salsbery31-May-07 9:30

Mark Salsbery

31-May-07 9:30

I see a few problems -

TheDelChop wrote:
GetObject(hSavedXYBitmap,sizeof(BITMAP),(LPSTR)(&bmp));

Irrelevent, but cast to a LPSTR?? No cast to a void pointer is necessary Wink | ;)

Problems:
Creating a BITMAPINFO the size of a BITMAPINFOHEADER.
Using the planes value from the DDB when it HAS to be 1 in a DIB.
bmiHeader.biSizeImage is calculated wrong - rows of pixel data in a DIB need to be DWORD aligned.
You've provided no color table (16-colors) for your destination 4-bit DIB
The resulting GetDIBits call should fail based on the above.

Something like this maybe will get you closer:

...
int nNumColors = 1 << cClrBits;
 
LONG lBytesPerRow = (((bmp.bmWidth * (long)cClrBits + 31L) & (~31L)) / 8L);
 
BYTE* pBitmapBits;
 
LONG SizeOfBitmapInfo = sizeof(BITMAPINFO) + ((nNumColors - 1) * sizeof(RGBQUAD));
  
BITMAPINFO *pbmi = (PBITMAPINFO) LocalAlloc(LPTR, SizeOfBitmapInfo);
memset(pbmi, 0, SizeOfBitmapInfo);
pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = 1;
pbmi->bmiHeader.biBitCount = cClrBits;
pbmi->bmiHeader.biCompression = BI_RGB;
pbmi->bmiHeader.biSizeImage = lBytesPerRow * bmp.bmHeight;
//pbmi->bmiHeader.biXPelsPerMeter = 0;
//pbmi->bmiHeader.biYPelsPerMeter = 0;
//pbmi->bmiHeader.biClrUsed = 0;
//pbmi->bmiHeader.biClrImportant = 0;
 
// I forget if you need to do this before GetDIBits() :doh:
//// Initialize color table
//for (int i = 0; i < nNumColors; i++)
//{
//   pbmi->bmiColors[i].rgbBlue = ; 
//   pbmi->bmiColors[i].rgbGreen = ; 
//   pbmi->bmiColors[i].rgbRed = ; 
//   pbmi->bmiColors[i].rgbReserved = 0; 
//}
 
pBitmapInfoHeader = (PBITMAPINFOHEADER)pbmi;
 
lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED,pbmi->bmiHeader.biSizeImage);
 
test = ::GetDIBits(hdc, hSavedXYBitmap, 0, (WORD) pbmi->bmiHeader.biHeight, lpBits, pbmi, DIB_RGB_COLORS);
if (test == 0)
   test = GetLastError();

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Newbie Question

joshp121731-May-07 8:45

joshp1217

31-May-07 8:45

I want to compile a project that I have created. The project has class objects separated in different files i.e. main.cpp, card.h, card.cpp, deck.h, deck.cpp. How am I able to do this so the deck class can create in instance of the card class i.e. vector<card*> x; I know this is really newbie but I got to know.

David Crow31-May-07 10:31

David Crow

31-May-07 10:31

joshp1217 wrote:
How am I able to do this so the deck class can create in instance of the card class

class deck
{
    deck();
    ~deck();
 
    card c;
}

Or you can do it in one of the deck's members:

void deck::foo( void )
{
    card c;
}

"A good athlete is the result of a good and worthy opponent." - David Crow

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

Matthew Faithfull31-May-07 11:10

31-May-07 11:10

Remember to make sure that all the files that use a type ( e.g card class ) have a #include line that references the file that defines the type.
If card is defined in card.h then deck.cpp might look something like this.

<br />
//deck.cpp<br />
<br />
#include "card.h"<br />
<br />
<br />
deck::deck()<br />
{<br />
  card the_cards[52];//An array of 52 cards for the deck<br />
}<br />

If the definition of deck itself, in deck.h, depends on the definition of card then it's deck.h that should #include "card.h"

Think of it as, when the compiler sees #include "card.h" it goes and reads the card.h file and after that it knows about the card class otherwise it's as if it never heard of it.
The trick is that every time it moves on to compiling a different .cpp file (compilation unit) it forgets everything it found out before and starts again knowning nothing except C++. Sounds dumb but it really works Wink | ;)

Nothing is exactly what it seems but everything with seems can be unpicked.

joshp121731-May-07 11:15

joshp1217

31-May-07 11:15

I thought that was how it should work but when I sent it up that way, i was getting errors like the Deck class didnt recognize the Card class because when i said vector<card*> m_Cards;(this is in the deck.h with #include "card.h" at the top) it basically would say that a vector cant have any empty type. The IDE i am using is Dev-C++ I dont know if that has anything to do with it but any further help would greatly be appreciated because I could do this with ease in C# but I need to do it in C++.

Matthew Faithfull31-May-07 11:37

Solution for those interested

31-May-07 11:37

Should that perhaps be vector<card> m_Cards; or did the html formatter just make your vector type parameter disappear? OMG | :OMG:

If not it might explain the empty type error, might even need #include<vector> and std::vector<card>m_Cards;
There's very little of the using AClass::BClass; stuff in C++ although
using namepsace std; works just fine and should let you use a vector as per the first example above. I'm no STL guru but then if you've done loads of C# you're no newbie either Big Grin | :-D

Nothing is exactly what it seems but everything with seems can be unpicked.

64 bit XP

Monty²31-May-07 7:40

Monty²

31-May-07 7:40

This Code fails on XP 64 bit even if the file exists in the target folder

The exe is 32 bit

CString str;
str = "C:\\WINDOWS\\system32\\drivers\\acpi.sys";

if(!PathFileExists(str))
{
     //Fails but the file exists and can be seen in explorer
     //fopen fails to with err=2 (invalid path)
}

i can paste any file in that folder (text file or whatever) and the result will be file not found (errcode=2)

it shows same behaviour in "c:\windows\system32" folder

So is there some security issue i am not seeing cause this thing runs fine in vista with UAC enabled

Thanks

Monty²31-May-07 22:41

Monty²

31-May-07 22:41

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1673046&SiteID=1[^]

C++ where friends have access to your private members !

Re: Solution for those interested

Mark Salsbery1-Jun-07 6:22

Mark Salsbery

1-Jun-07 6:22

Good to know! Thanks for the update!

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Registry vs .Ini files.

Anurag Gandhi31-May-07 7:37

Anurag Gandhi

31-May-07 7:37

Hi all,
I want to know that which is the better and faster way to access, read and write configuration settings: .ini files or windows registry. Speed matters much for me.
Please help me.

Anurag Gandhi.

David Crow31-May-07 7:57

David Crow

31-May-07 7:57

Anurag Gandhi wrote:
Speed matters much for me.

It sounds as though you need some other storage mechanism then. Neither INI files nor the registry are meant for heavy-duty (constant) access where speed is critical.

"A good athlete is the result of a good and worthy opponent." - David Crow

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

Anurag Gandhi31-May-07 8:00

Anurag Gandhi

31-May-07 8:00

Thanks for reply.
But then, tell me the better way of storing the congiuration settings.
Thanking you in advance.

Anurag Gandhi.

David Crow31-May-07 8:15

David Crow

31-May-07 8:15

Anurag Gandhi wrote:
But then, tell me the better way of storing the congiuration settings.

By "congiuration settings," I assume you mean settings that are read once at program startup, and written once at program shutdown or via some Properties dialog?

"A good athlete is the result of a good and worthy opponent." - David Crow

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

Anurag Gandhi31-May-07 8:17

Anurag Gandhi

31-May-07 8:17

Exactly.
Any idea about that? Which method is faster?

Anurag Gandhi.