Re: Problem in deleting entries from Hash_set

From:

Joe Greer <jgreer@doubletake.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 7 Mar 2009 18:04:40 +0000 (UTC)

Message-ID:

<Xns9BC7850923C5Bjgreerdoubletakecom@85.214.105.209>

Prafulla T <prafulla.tekawade@gmail.com> wrote in news:3e695b9b-1c2c-4416-
ba28-9c21337ee0ba@p6g2000pre.googlegroups.com:

Is following correct way of deleting entries from stl hashset.
Will it create any memory corruption ?
One of my program uses this way and it is crashing in strange way but
purify or valgrind does not
show up anything. I am suspecting this piece of code as a problem.
Can anyone comment on it ?

    for (hash_set<UserType*>::iterator hashIt = hashSet.begin();
         hashIt != hashSet.end(); hashIt++)
    {
        UserType *pUserType = *hashIt;
        hashIt++;
        delete pUserType;
        pUserType = NULL;
    }

Hmmm, does your hash_set::erase() perhaps return an iterator? If so, the
loop you want probably looks something like.

for (hash_set<UserType *>::iterator hashIt = hashSet.begin();
   hashIt != hashSet.end();)
{
   UserType *pUserType = *hashIt;
   hashIt = hashSet.erase(hashIt);
   delete pUserType;
}

That should delete every item in your hash_set and delete the elements as
well.

HTH

joe