From: david DOT stegbauer AT cz DOT opel DOT com
X-Lotus-FromDomain: GMCZECHIA AT EDSHUBEUROPE
Sender: david DOT stegbauer AT cz DOT opel DOT com
To: chris DOT jones AT ucl DOT ac DOT uk
cc: djgpp AT delorie DOT com
Message-ID: <41256753.0045CCC7.00@derumg01.cyberlink.eds.com>
Date: Wed, 14 Apr 1999 11:36:16 +0000
Subject: Re: SIGSEGV problem with DJGPP (deleting array)
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Reply-To: djgpp AT delorie DOT com



Chris Jones <chris DOT jones AT ucl DOT ac DOT uk> wrote:
> The idea is to increase the size
> of the array ptr by one, so I copy to a dummy array, delete ptr and recreate
> it with a new, larger size. Then copy the old contents across from the dummy
> array and delete it.

This is not very effcient. Suppose you store pointer 'ptr' in your class,
then you can make a copy only once and assign new array pointer
to your class pointer.

Here is snip from my Array template - if you are interested, I can send
you whole code separately.

David Stegbauer
----
const int delta = 16;    /*allocate space by 'delta' items to avoid unnecessary
resizing*/
template < class T >
class Array
{
public:
     Array (int size=0, bool autosize = true);
     ~Array ();
     int resize (int size);
     /* and other methods, including operator[], snipped here*/
private:
     int _last_used;          //last used index, -1 if empty
     int _size;     //how much _data can be hold (max possible _last_used is one
 less
     T *_data;
public:
     bool _autosize;
};

template < class T >
inline Array<T>::Array (int size=0, bool autosize = true)
          :_last_used(-1), _size(size), _data(0), _autosize(autosize)
{
   resize(size);
}

template < class T >
Array<T>::~Array()
{
   if (_data) delete[]_data;
}

template < class T >
int Array < T > ::resize (int size)
{
     if (size == _size)
          return _size;
     if (size < _last_used+1)
          _last_used = size - 1;
     size = ((size - 1) / delta + 1) * delta;
     T *tmp = new T[size];
          T* tmpx = tmp;
  for (int i = 0; i < _last_used; ++i)
      {
          *tmpx++ = *_data++;
      }
  delete[]_data;
  _data = tmp;
  int old_capacity = _size;
  _size = size;
  return old_capacity;
}