Re: Crash in erasing element of a list.

From:
"Heinz Ozwirk" <hozwirk.SPAM@arcor.de>
Newsgroups:
comp.lang.c++
Date:
Mon, 10 Jul 2006 23:11:05 +0200
Message-ID:
<44b2c26a$0$26262$9b4e6d93@newsread2.arcor-online.net>
"red floyd" <no.spam@here.dude> schrieb im Newsbeitrag
news:%Twsg.129149$dW3.113007@newssvr21.news.prodigy.com...

mahajan.vibhor@gmail.com wrote:

I have a list of pointers. e.g

A* a = new A(); // A is a class
stl::list<A*> list_a;

I am inserting object of class in the after allocating memeory thru new
operator.

But when i want to erase all elements from the list. my progam crashes.
I delete element by using a iterator.

A * temp = NULL;
stl::list<A*>::iterator Iter,
stl::list<A*>::iterator IterTemp;
for( Iter = list_a.begin() ; Iter != list_a.end() ; ){
           Iter = list_a.begin();
           temp = *Iter;
           IterTemp = Iter;
           Iter++;
           list_a.erase(IterTemp);
           delete temp;
}

At erase line my program crashes and debugger shows some exception in
erase function.


First of all, it should be std::list, not stl::list.

Second, rewrite your delete loop as follows:

for (iter = list_a.begin(); iter != list_a.end ; )
{
    delete (*iter);
    iter = list_a.erase(iter);


Or perhaps even better:

    list_a.erase(iter++);

This will work for all STL containers, not just those where erase returns an
iterator to the next element.

    Heinz

}

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