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  4. Converting CString to char*

Converting CString to char*

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  • Z zafersavas

    Hi super_ttd, What's the problem with CString::GetBuffer()? Why dont you like it? :)

    C Offline
    C Offline
    Cedric Moonen
    wrote on last edited by
    #11

    Read the documentation about CString::GetBuffer and you will see why you have to absolutely avoids it if you don't know exactly what you are doing.

    Cédric Moonen Software developer
    Charting control [v1.5] OpenGL game tutorial in C++

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    • S super_ttd

      It should do. So, what's wrong ? Do you get an error ? CString has an inner cast Operator (LPCTSTR) which converts the CString object to a const char* (if compiling ANSI) of const wchar_t* (if building unicode), so you should not have to do any much stuff. And please (if you get this advice from anywhere), don't use the CString::GetBuffer()) method at all for such a thing !!! So, to come back to you problem, what is your problem ?


      D Offline
      D Offline
      DSPCottage
      wrote on last edited by
      #12

      Visual C++ 2005 doesn't support (LPCTSTR) cast operator. thus I need an interface to change a CString object to a char* exactly now I am porting an project from VC6 to VC2005 and it is my problem Regards Mahdi

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      • M Mark Salsbery

        GetBuffer() is completely unnecessary when you're only reading the string (i.e. when you only need a const pointer to the string's internal buffer). The LPCSTR operator is safe and more efficient. GetBuffer() is for when you need a non-const pointer.

        Mark Salsbery Microsoft MVP - Visual C++ :java:

        D Offline
        D Offline
        DSPCottage
        wrote on last edited by
        #13

        But it appears that VC2005 doesn't support (LPSTR) or (LPCTSTR) operator. isn't it? Regards

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        • M Mark Salsbery

          In addition to super_ttd's reply... If you must use fopen(), then you should probably use a CStringA. CString has a generic internal character type, depending on whether UNICODE or _UNICODE is defined. If you want to use the generic text CString, then it will pair nicely with the generic text version of fopen(), which is _tfopen().

          Gut Mikh Tappe wrote:

          char buffer[MAX_PATH]; GetModuleFileName(NULL,(LPWCH)buffer,MAX_PATH);

          Bad cast!! GetModuleFileName takes a LPTSTR as its second parameter. Your buffer, therefore, should be a TCHAR type, not char. Mind your types.....if you need a cast to get something to compile, look at WHY. Mark

          Mark Salsbery Microsoft MVP - Visual C++ :java:

          D Offline
          D Offline
          DSPCottage
          wrote on last edited by
          #14

          May you please give me an article about UNICODE ? Regards Mahdi

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          • L led mike

            Gut Mikh Tappe wrote:

            Please let me know what to do

            Ok I will try. What you need to do is read the documentation.[^] Also reading this might help as well.[^] In my experience not all authors match every reader. So if you find reading those sources don't supply your need 100% keep looking for more. The bottom line is what you need to do is read and study rather than type code and forum messages.

            led mike

            C Offline
            C Offline
            Cedric Moonen
            wrote on last edited by
            #15

            led mike wrote:

            Also reading this might help as well.[^]

            I think that is the best choice to start with :)

            Cédric Moonen Software developer
            Charting control [v1.5] OpenGL game tutorial in C++

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            • D DSPCottage

              But it appears that VC2005 doesn't support (LPSTR) or (LPCTSTR) operator. isn't it? Regards

              C Offline
              C Offline
              Cedric Moonen
              wrote on last edited by
              #16

              Yes, it is simply because UNICODE is defined by default (which was not the case with VC6). I strongly suggest that you read the article given by Led Mike, things will be much more clear afterwards.

              Cédric Moonen Software developer
              Charting control [v1.5] OpenGL game tutorial in C++

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              • D DSPCottage

                But it appears that VC2005 doesn't support (LPSTR) or (LPCTSTR) operator. isn't it? Regards

                M Offline
                M Offline
                Mark Salsbery
                wrote on last edited by
                #17

                The operator is a member of the CSimpleStringT class, which is the base class of CStringT. The actual operator is PCXSTR (the ATL type), which is the equivalent of LPCTSTR (a Win32 type). Here's your code using generic text types:

                TCHAR buffer[MAX_PATH];
                GetModuleFileName(NULL,buffer,MAX_PATH);
                CString path = buffer;
                path = path.Left(path.ReverseFind(_T('\\'))+1);
                path += _T("result.mp3");
                f = _tfopen( path , _T("wb")); // <-- implicitly uses CString's PCXSTR operator!

                See Generic-Text Mappings in Tchar.h[^] and for Unicode info: International Programming[^] Mark

                Mark Salsbery Microsoft MVP - Visual C++ :java:

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                • L led mike

                  Gut Mikh Tappe wrote:

                  Please let me know what to do

                  Ok I will try. What you need to do is read the documentation.[^] Also reading this might help as well.[^] In my experience not all authors match every reader. So if you find reading those sources don't supply your need 100% keep looking for more. The bottom line is what you need to do is read and study rather than type code and forum messages.

                  led mike

                  M Offline
                  M Offline
                  Mark Salsbery
                  wrote on last edited by
                  #18

                  led mike wrote:

                  Also reading this might help as well.[^]

                  That IS a good link. I bookmarked that to post in the future, Thanks! :beer:

                  Mark Salsbery Microsoft MVP - Visual C++ :java:

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                  • D DSPCottage

                    May you please give me an article about UNICODE ? Regards Mahdi

                    R Offline
                    R Offline
                    Rick York
                    wrote on last edited by
                    #19

                    Here are a few : http://www.google.com/search?hl=en&q=UNICODE&btnG=Google+Search[^]

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                    • Z zafersavas

                      There a various ways: 1)

                      CString str = "filename";

                      char charPtr[100];
                      sprintf(charPtr, "%s", str);

                      CString str = "filename";
                      char* charPtr = str.GetBuffer(str.GetLength());

                      S Offline
                      S Offline
                      super_ttd
                      wrote on last edited by
                      #20

                      zafersavas wrote:

                      str.GetBuffer(str.GetLength());

                      Memory Leak here ! Why the hell do people use that dangerous GetBuffer() function when it's absolutely useless ? :doh:


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