Assignment of a Singular Iterator

Question

A \"Singular Iterator\" is defined as an:

iterators that are not associated with any sequence. A null pointer, as well as a default-constructed pointer (

Answer 1

Regarding the example for the second question, it works fine because and is well-defined, because you don't actually dereference the pointer foo. The variable foo is initialized, all you are doing is initializing a variable with another initialized variable. It's no different from e.g.

int foo = 0;
auto bar = foo;

However, if you did e.g.

int* foo = nullptr;
auto bar = *foo;

that would be UB because you dereference a null pointer.

Also, Undefined behavior is, well, undefined... It might seem to run fine but in reality it's really not.