Should we delete before or after erase for an pointer in the vector?

Question

Should we delete before or after erase. My understanding is both are OK. Is it correct?

In addition, is there any case we won't want to delete the element while erasing it? I believe there must be , otherwise, the erase will be happy to take the responsibility.

std::vector<foo*> bar;
...
for (vector<foo*>::iterator itr = bar.begin(); itr != bar.end(); itr++)
{
   delete (*itr);  //before OR
   bar.erase(itr);
   delete (*itr);  //after???
}

Answer 1

"itr" must be used like this;

for (vector<foo*>::iterator itr = bar.begin(); itr != bar.end(); )
{
   delete (*itr);
   itr = bar.erase(itr);
}

However, I'd prefer to first delete all elements, and then clear the vector;

for (vector<foo*>::iterator itr = bar.begin(); itr != bar.end(); ++itr)
   delete (*itr);
bar.clear();