map::erase

[Viral Shah]

I have a map<int, obj>. When I do a map::erase(iterator), does this call the
destructor of the object? Or does it just remove that entry from the map.

 

[Victor Bazarov]

I have a map<int, obj>. When I do a map::erase(iterator), does this call the
destructor of the object? Or does it just remove that entry from the map.

The entry in the map _contains_ the object. Of course while removing the
entry, it _has_to_ destroy the object.

V

 

[John Dibling]

I have a map<int, obj>. When I do a map::erase(iterator), does this call the
destructor of the object? Or does it just remove that entry from the map.

It calls the destructor. A note: if the map is actually a map of
pointers to obj's and not actually obj's themselves, then what is
destroyed is the pointer to the obj - not the obj itself. In other
words, erase doesn't call 'delete' for you if the map is declared like
this: 'map<int, obj*>'.

Take care,

John Dibling

 

[verec]

It calls the destructor. A note: if the map is actually a map of
pointers to obj's and not actually obj's themselves, then what is
destroyed is the pointer to the obj - not the obj itself. In other
words, erase doesn't call 'delete' for you if the map is declared like
this: 'map<int, obj*>'.

But it *does* call delete if your map is of the form map<int, smart_ptr<T> >
for some suitable definition of smart_ptr<T>

I know: I'm using this all the time

 

[Victor Bazarov]

But it *does* call delete if your map is of the form map<int,
smart_ptr<T> > for some suitable definition of smart_ptr<T>

I know: I'm using this all the time

But that's not the feature of the map. It's the destruction of the
'smart_ptr<T>' object what does the 'delete'ion.

V

 

[verec]

But that's not the feature of the map. It's the destruction of the
'smart_ptr<T>' object what does the 'delete'ion.

Yep. That's the point of using something that can sort of "delegate"
the destruction to the real thing, yet also pose as, the real thing
when accessed from the map.