Re: Making this code generic with C++ Standard Lib

"David Webber" <>
Wed, 22 Aug 2007 10:13:20 +0100
"Jack" <> wrote in message

"Ulrich Eckhardt" <>

Jack wrote:

 vector<D3DXFRAME_EX>& Find (std::string& FrameName)


  return NULL;

'NULL' is not a vector<>.


Dear Uli,
Thanks for your prompt reply. I wonder how to get around this?

You need to learn the differences between pointers, references, and vector
classes. Ulrich's point was just one of the many things wrong with the
follwoing function (which, in your second version, seems to be a member of
struct D3DXFRAME_EX ). I'll intersperse some comments:

vector<D3DXFRAME_EX>& Find (std::string& FrameName)
  vector<D3DXFRAME_EX> pFrame;
     vector<D3DXFRAME_EX> pFramePtr;

    //----you have defined two empty vectors.

  if (Name && FrameName.c_str() && !
   return this;

   //-- Is "Name" a member of a base class of D3DXFRAME_EX ????
   // Why are you returning a pointer to a struct D3DXFRAME_EX
  // when the function is defined to return a reference to a vector of them?

  if (pFramePtr == (vector<D3DXFRAME_EX>)pFrameSibling)
   if ((pFrame = pFramePtr.Find(FrameName)))
    return pFrame;

    // What is pFrameSibling??
    // Whatever it is, why are you testing to see if the empty
    // vector you have just declared is equal to it, (when you cast it to a
    // Are you searching for FrameName in the other emty
    // vector you just declared? You know you can't find it.
    // Why are you returning a reference to a local variable when it will
    // be out of scope as soon as you get out?

  if (pFramePtr == (vector<D3DXFRAME_EX>)pFrameFirstChild)
   if (pFrame = pFramePtr.Find(FrameName))
    return pFrame;

    // Same questions apply.

  return NULL;

    // and as Ulrich said NULL isn't a vector either.


This function just displays so many complete misconceptions about C++ ....
structures, classes, STL classes, functions, pointers, references, local
variables, scope, .... that I really do recommend starting with something
easier if you want to learn C++. There is surely no way that anyone here
can work out what this function is attempting to do. (From the names it
seems to be to do with finding something in a vector, but that's just a


David Webber
Author of 'Mozart the Music Processor'
For discussion/support see

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