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vb-c++-connection

Discussion in 'Visual Basic ( VB )' started by AMK, Sep 9, 2006.

  1. AMK

    AMK New Member

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    c++ dll has exported funtion call such as:
    void AccessUnknownBuf(char** cbuffer, int sizeofbuf);
    VB does not know about the size of cbuffer beforehand. It has to get the cbuffer and its size from dll. How VB can do this?. somehow it should be accessing dll's memory area...?. seconldy, how to allocate more than 40000 bytes for character string type?.
    dim s as string*50000 does not work.
     
  2. AMK

    AMK New Member

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    It is actually like this:
    void AccessUnknownBuf(char** cbuffer, int* sizeofcbuffer);
     
  3. shabbir

    shabbir Administrator Staff Member

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    AccessUnknownBuf should supply the size of the buffer for some default parameter and in VB use the string with SPACE to fill the buffer and pass that as an argument to the function.
     
  4. AMK

    AMK New Member

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    how do you allocate this many mem space to string?.
    Dim s as string*50000 (got overflow error).
     
  5. shabbir

    shabbir Administrator Staff Member

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    Code:
    Dim str As String
    str = Space(1000)
    This will allocate the string with 1000 buffer size by default and this can be used easily with the C++ buffer.
     
  6. AMK

    AMK New Member

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    there is no way that i can access c++ dll's cBuffer content without allocating memory in VB?.
     
  7. shabbir

    shabbir Administrator Staff Member

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    I dont think so. You are calling a function in a C++ dll and all you can get is the return type of the function or any pointer that you provide are having some data and the second option requires you to have the buffer in VB and pass that to C++ dll.
     

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