C / C++ / MFC

Re: VS NET. 2003 strange characters in MFC project?

1-Nov-05 23:26

Yes, it's chinese by default. Annoying, isn't it? Mad | :mad:

Prakash Nadar1-Nov-05 23:56

Re: VS NET. 2003 strange characters in MFC project?

1-Nov-05 23:56

or a version pirated from China

-prakash

Jörgen Sigvardsson2-Nov-05 0:03

Strings really messed up between VC++ and VB

2-Nov-05 0:03

Mine's a pure and legal MSDN Universal copy. Still Chinese by default.

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Axonn Echysttas1-Nov-05 22:37

1-Nov-05 22:37

Hi everybody. I got a question related to an article for the Code Project I'm working at. I got this function in VC++ which returns a structure to VB. The structure contains a long member and a BSTR member. In VB the structure contains a long member and a String member, so their data types are matched. Ok. With the long member, there are no problems.

However, when I put a text in the BSTR member, like this:

cmResponse.theBSTR = SysAllocString(ConvertCharToBSTR("String added in <br />
VC++"));

(I pasted the ConvertCharToBSTR function at the end of this message)
I get the following data back in VB:
"S|t|r|i|n|g| |a|d|d|e|d| |i|n| |V|C|+|+|"

That | is actually some weird character. Of course, I realize this is probably some data type alignment issue. I tried sending char but with no use: VB requires SysAllocString to allocate the string in order to successfully receive it. Also, I think the String type from VB is not UNICODE while C++ sends an Unicode. I did make it work (although this is not entirely correct) like this:

LPCWSTR test = (LPCWSTR)"testing";<br />
cmResponse.sFifth = SysAllocString(test);

However, because "testing" has 7 letters, I get an eight character in VB : "|". So in VB it looks like this "testing|". If I write "testin" it's ok since it has 6 characters.

So what could be the problem? How can I do it to get this string correctly to VB? So far, the only solution I can figure out is to allocate a number of characters equal to the lenght of the string divided by 2 using SysAllocString, then if the string has an un-even number of characters, add a space to it. Which of course is an ugly solution.

Here's the ConvertCharToBSTR function, for all that matters...

//Converts a Char to a BSTR. Needed when working with strings with Visual Basic.<br />
BSTR ConvertCharToBSTR(char* CharValue)<br />
{<br />
	int i; //Iteration counter.<br />
	int iLength = strlen(CharValue); //Finding out the length of the Char.<br />
	unsigned short* bstrResult = new unsigned short[iLength + 1]; //Creating a BSTR with the required length.<br />
<br />
	//Going through the Char characters.<br />
	for (i = 0; i < iLength; i++)<br />
	{<br />
		char iCharacter = CharValue[i]; //Taking the next char.<br />
		bstrResult[i] = iCharacter; //Adding it to the string.<br />
		bstrResult[i + 1] = '\0'; //Adding the null-termination to the string.	<br />
	}<br />
	return bstrResult; //Returning the result.<br />
}

-= E C H Y S T T A S =-
The Greater Mind Balance

Prakash Nadar1-Nov-05 23:03

1-Nov-05 23:03

ConvertCharToBSTR looks very messy function, could you not consider using _bstr_t[^]

-prakash

Axonn Echysttas1-Nov-05 23:44

1-Nov-05 23:44

Doesn't work.

I put:

_bstr_t sTest = "Testing";<br />
cmResponse.sFifth = sTest;

Where sFifth is a _bstr_t. The VB application crashes when doing so.

-= E C H Y S T T A S =-
The Greater Mind Balance

Prakash Nadar1-Nov-05 23:52

1-Nov-05 23:52

Axonn Echysttas wrote:
cmResponse.sFifth = sTest;

cmResponse.sFifth = sTest.Detach(); is the right way to use it

sFifth should also be BSTR

-prakash

-- modified at 5:53 Wednesday 2nd November, 2005

Axonn Echysttas2-Nov-05 0:50

2-Nov-05 0:50

Hm.

error C2039: 'Detach' : is not a member of '_bstr_t'

-= E C H Y S T T A S =-
The Greater Mind Balance

Prakash Nadar2-Nov-05 4:55

2-Nov-05 4:55

did you include comutil.h ?

-prakash

Axonn Echysttas2-Nov-05 7:00

2-Nov-05 7:00

Of course I did! : ). Anyway, the right way to do it is _variant_t, just thought you people want to know. With that it works ok, even if there are still some minor issues.

-= E C H Y S T T A S =-
The Greater Mind Balance

Prakash Nadar2-Nov-05 15:33

2-Nov-05 15:33

Axonn Echysttas wrote:
Anyway, the right way to do it is _variant_t

ofcource I know that, But since BSTR worked for you in the first place I was keeping the solution simple for you.

-prakash

Jörgen Sigvardsson1-Nov-05 23:29

1-Nov-05 23:29

Ehm. You really need to read this[^] and this[^], because you're really on thin ice (about 40 Angstrom thick) when it comes to string handling right now...

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Axonn Echysttas2-Nov-05 3:26

2-Nov-05 3:26

Thanks. Yeap, I looked over it and I found the _variant_t type to help me. However, I would prefer being able to use the basic types such as LPCWSTR to solve the problem. Sending LPCWSTR to VB works but if sending un-even number of characters such as "a" or "abc" it adds that | character at the end. If I could solve this in an easy way it would be perfect.

-= E C H Y S T T A S =-
The Greater Mind Balance

Jörgen Sigvardsson2-Nov-05 3:35

2-Nov-05 3:35

You get the errors most likely because you are forcing an ASCII string into SysAllocString(). Try this instead: SysAllocString(L"This is a wide string"). Notice the L-prefix?

If you are using MFC7/ATL7.x, you could use CComBSTR() as it takes an ordinary ASCII string as parameter in one of its constructors. Otherwise, please look up the function MultiByteToWideChar() which performs ASCII -> wide for you.

Also, please be wary when dealing with BSTR strings. They are not regular wide strings as the articles I mentioned above says.

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Axonn Echysttas2-Nov-05 4:26

2-Nov-05 4:26

Yeah, it's pretty weird. I get a thousand weird issues while working with Strings from VC++ to VB. Very annoying.

-= E C H Y S T T A S =-
The Greater Mind Balance