default pointer values in map when using operator[]

Question

Is a pointer inserted into a map due to a missing index always NULL?

std::map<int, Foo*> myMap;
Foo* myFoo = myMap[0];

Is myFoo guaranteed to be NULL?

Answer 1

From cppreference:

If an insertion is performed, the mapped value is value-initialized (default-constructed for class types, zero-initialized otherwise) and a reference to it is returned

So yes, this is guaranteed to be NULL.

Answer 2

Yes, when a missing index is accessed, it is value-initialized, implying a null pointer is returned in this case (as it is a scalar value).

Source : http://en.cppreference.com/w/cpp/container/map/operator_at