RE: [Dev-C++] Generic C++ question.

[Ioannis V. <no...@ho...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of J Miller
> Sent: Thursday, May 16, 2002 4:03 AM
> To: Dev-C++ Users (E-mail)
> Subject: [Dev-C++] Generic C++ question.
> 
> 
> Hi all,
> 
> If a method returns a char pointer (char*).
> 
> If the above method does a malloc() to allocate memory
> for some text (or something) and then fills that memory.
> 
> The char* is returned to the user code.
> 
> Who (or which code) is responsible for doing a free() on the char*?
> 
> John M'

In C++ DO NOT USE malloc()/free(). malloc()/free() do  not call the
objects' constructors and destructors. In C++ use only new, delete,
new[] and delete[].

The caller of the function is responsible to clear the memory returned
by the called function, if it allocated memory on the free store.

E.g.:

char *something()
{
 char *p=new char[100];

 for(int i=0; i<100; i++)
   p[i]='a';

return p;
}


int main()
{
 char *ptr=something();

  // play with ptr

  delete[] ptr;
}


In C++ avoid programming in such low level. Use the standard library
containers instead which supress any need for explicit  resource
allocation and deallocation. For example:


#include <vector>

const std::vector<char> something()
{
  using std::vector;
  
  vector<char>p(100);
  
  for(vector<char>::size_type i=0; i<p.size(); i++)
     p[i]='a';
     
  return p;
}


int main()
{
  using namespace std;
  
  vector<char>array=something();
  
  // play with array


// array is destroyed automatically, all its contents
// are cleared, element desttructors are called. No possibility
// for memory leak (and in general for ANY resource leak!)
}  


If you find that the vector<char> return of something() is expensive,
you can pass the "array" vector to something() by reference and fill it
there.

In summary, try to use C++ as a high level language and not as low level
one. There is much to gain from that. Unfortunately it usually is
teached and used in low level style (usually by C programmers since C++
is  very newly "official" language, it got standardised just in 1998).



Ioannis

* Ioannis Vranos
* Programming pages: http://www.noicys.cjb.net
* Alternative URL: http://run.to/noicys