Re: question about new and delete operator

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Mon, 6 Jul 2009 02:58:40 -0700 (PDT)

Message-ID:

<46068f39-e539-41af-9d98-79e1e26a8cca@t33g2000yqe.googlegroups.com>

On Jul 5, 10:39 pm, Hendrik Schober <spamt...@gmx.de> wrote:

Lars Tetzlaff wrote:

LiDongning schrieb:

I'm working on a class which allocate some memory to store
an array (pointed by a pointer p_data). In constructor I
use new to do the allocation, in destructer I use delete to
free the memory. In one member function I wan to do
something with the data (say, sort). In that case, inside
that function, I plan to allocate a piece memory to store
the processed data (p_processed), then free the original
memory (p_data), and point the p_data to p_process. The
code will be something like attached below. My question is,
can i do something like in the last two lines of code? Will
this cause a memory leak or any harmful effect? Thanks very
much!

I would recommend to use std::vector like this:

#include <vector>

template <class T>
class data
{
  std::vector<T> m_data;
public:
  data(int, T*);
  void process();
};

template <class T>
data<T>::data(int in_n, T* in_data)
: m_data( in_data, in_data + in_n )
{
}

Why 'int'? Will there ever be a sequence of -5 bytes?

Because int is the "standard" type for integral values in C++.
Anything else should only be used if int won't do the job; the
only justification for not using int here would be that there
might be sequences of more that INT_MAX bytes.

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James Kanze (GABI Software) email:james.kanze@gmail.com
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