g++ STL container element deletion.

[Colin Thomas <colin at designresources dot co dot uk>]

Hi,

I have a question pertaining to STL containers.

I create a number of string pointers, and add them to
a vector.

At some later date I wish to delete ALL of the pointers
and want to use the container to do this.

When I observe memory usage through UNIX "top" though, the
memory is not being freed.

The C++ code looks like:

/////////////////////////////////////////////////////////
#include <string>
#include <vector>
#include <utility>
#include <exception>
#include <cstdio>
#include <ctime>
#include <algorithm>

using namespace std;
///////////////////////////////////
int main()
{
 unsigned int i;
 char         str[256];

 vector<string *>           thisStringVector ;
 vector<string *>::iterator thisStringVectorElement ;

 /////////////////////////
 //Create 1000000 string pointers and add to the vector
 //
 for (i = 0 ; i < 1000000 ; i++) 
 {
  //Create a new string pointer...
  string * pThisString;
  try {
   pThisString = new string ;
  }
  catch (...) {
   cout << "Error in pThisString allocation...\n";
  }
  (*pThisString) = "A";
  thisStringVector.push_back(pThisString);
 }
 
 /////////////////////////
 //Delete 1000000 string pointers 
 //
 for( thisStringVectorElement  =   thisStringVector.begin();
      thisStringVectorElement !=   thisStringVector.end();
      thisStringVectorElement++
    )
 {
  //Delete the string contents
  (**thisStringVectorElement).erase( 
                                    (**thisStringVectorElement).begin() ,
                                    (**thisStringVectorElement).end()
                                   );
  //Delete the pointer to the strinf & free-up memory
  delete (*thisStringVectorElement);
 }
}
/////////////////////////////////////////////////////////

I am running GNUCC2.95.2.

I have discussed this with some other developers (VC++) and
they say this code should delete the string pointers, and free
up memory.

If there an implementaion issue with g++ STL containers OR are
my VC++ associated incorrect in their beliefs.

I lok forward to your combined wisdom.

Many thanks in advance..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Colin Thomas. 
| Design Consultant.                             
|                                           
| Email   : colin@designresources.co.uk     
| Tele    : (44) 1234 240562 
| Fax     : (44) 1234 241262               
|                                           
| Address : Design Resources,
|           27 Market Place,             
|           Olney,                           
|           Buckinghamshire,                
|           United Kingdom.                 
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