CODEWITHSUNDEEP
c++visual-c++
codrgii
codrgii

Reputation: 209

delete and erasing an iter?

i'm initializing and inserting into a list like so

_ARRAY_DETAIL* pAR = new _ARRAY_DETAIL;
pAR->sVar1 = 1;
pAR->nVar2 = 2;
m_SomeList.push_back(pAR);

i am trying to find and erase all from the list that contains the value 1, and then delete the pointer we created with new, is my example below doing both in a good, correct efficient way?

while(Iter != m_SomeList.end());
{
    if((*Iter)->sVar1 == 1) 
    {
        _ARRAY_DETAIL* pAR = *Iter;
        Iter = m_SomeList.erase(Iter);
        delete  pAR;    pAR = NULL;
    }

    Iter++;
}

Upvotes: 2

Views: 576

Answers (2)

Mark Ransom
Mark Ransom

Reputation: 308206

Once you erase the iterator, it's no longer valid. You need to increment it before the erase.

if((*Iter)->sVar1 == 1) 
{
    _ARRAY_DETAIL* pAR = *Iter;
    m_SomeList.erase(Iter++);
    delete pAR;
}
else
    ++Iter;

You were correct that erase returns an incremented iterator but I prefer to do it explicitly, before the iterator is erased.

Setting pAR to NULL is redundant, since it's going out of scope on the next line anyway.

Also note that you should only increment Iter if you didn't increment it in the other part of the if.

Upvotes: 2

keety
keety

Reputation: 17441

as an alternative you could use remove if although what you have done seems fine. 

 bool IsOne (_ARRAY_DETAIL* pAR) { 
   if(pAR->sVar1 == 1) {
    delete pAR;
    return true;
   }
   return false;
 }

 remove_if (vec.begin(), vec.end(), IsOne);

Upvotes: 1

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