CString into string

[eranga262154]

Hi all,

What is the easiest way to convert a CString into a standard C++ sting.

Thanks

[Ancient Dragon]

CString mystring = _TEXT("Hello World");

string astring = (LPCTSTR)mystring; // assuming UNICODE is NOT defined
or
string astring = mystring.GetBuffer(0);

[eranga262154]

Thanks,

How about this way...

string MyStr( (const char*)MyCStringObject );

[Ancient Dragon]

>>How about this way...
You will have to try it to find out because I don't know if that will work or not with the most recent version of MFC supplied with VC++ 2005. Microsoft made a lot of changes to it, including making it a template instead of a c++ class.

[FireNet]

Thanks,

How about this way...

string MyStr( (const char*)MyCStringObject );

Old style cast.

Read:
http://msdn2.microsoft.com/en-us/library/ms174288(VS.80).aspx
http://msdn2.microsoft.com/en-us/library/awkwbzyc(VS.80).aspx

[eranga262154]

Ok, I've done it in this way.

std::string strRTF(ss.GetString());

and no compiled error at all.

To check it simply I used

cout << strRTF;

, here I got a compile error.

binary '<<' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion)

I can't find why is that. Everything is done on console application with MFC support. So this should work.

[Ancient Dragon]

did you include <string> at the top of your program?

[eranga262154]

Of course. And also preceding everything with std:: but still it not work. Here is my code, why I'm confusing is the first cout works, but not the second one.

if(m_rtfCtrl.CreateEx(WS_EX_APPWINDOW, WS_BORDER|ES_MULTILINE, CRect(10,10,200,200), &x , 1))
		{
			CString ss;
			CFile rtfFile;
			BOOL err = rtfFile.Open("G:\\Work On\\CPP\\RTFControl\\TestFile.rtf", CFile::modeReadWrite, NULL);

			int iLength = rtfFile.GetLength();// Data length
			char *pBuffer = new char[iLength];// Data buffer

			rtfFile.Read(pBuffer, iLength);
			CString rtf(pBuffer);

			m_rtfCtrl.SetWindowText(rtf);
			m_rtfCtrl.GetWindowText(ss);

			std::cout << ss << std::endl;

			// CString into string
			std::string strRTF(ss.GetString());
			
			std::cout << strRTF << std::endl;

		}

[Ancient Dragon]

Are you certain you are talking about line 21? It would seem more reasonable that line 16 should give you that error because ss is a CString object and cout doesn't know out to output it, or CString doesn't have an << operator for cout unless of course you wrote it yourself.

[eranga262154]

I'm not clear. I got it in this way, line 16 can be effect on line 21? I've comments the line 16 and still the issue is there.

[eranga262154]

Hey, I found it. That strRTF should be a null-terminated string, so I change the line 21 as follows.

cout << strRTF.c_str();

But why it is necessary. Work on console application and cout is a standard iostream object.

[Ancient Dragon]

Actually it doesn't really matter about that error because cout can not print to any MFC (or non-MFC) window. The output is just tossed into the bit bucket by the os. If you want to see debug messages then use MessageBox().

[FireNet]

Or over load the << operator for an ostringstream inheriting class and pipe all the output to into a text box.

eg...

class mfc_text_box : public ostringstream
{
//pseudo -code
operator << (Cstring &x)
{
 write_txt_to_box(x.c_str());
}

}

Then you can use a mfc_text_box_obj just like cout.

[eranga262154]

Actually it doesn't really matter about that error because cout can not print to any MFC (or non-MFC) window. The output is just tossed into the bit bucket by the os. If you want to see debug messages then use MessageBox().

Even I use a MessageBox() I have to use a null-terminated string there. :(

[Ancient Dragon]

No you can use the CString object directly

CString str = _TEXT("Hello World");
AfxMessageBox(str,MB_OK);

or

CString str = _TEXT("Hello World");
MessageBox(str.GetBuffer(),"Debug Message",MB_OK);

[eranga262154]

Ya, that is true. But can't do this in my application with strRTF string without null-terminating.

AfxMessageBox(strRTF,MB_OK);

Not work,

AfxMessageBox(strRTF.c_str(),MB_OK);

Works.

[Ancient Dragon]

AfxMessageBox takes a const char* or the ID (unsigned int) of a string resource.

[eranga262154]

Yes that is true. First parameter points to either CString object or null-terminated string. So here I have to use a null terminated string. Now its clear to me.