Difference between : list

Question

if i have a class "Movie" as follows:(c++)

class Movie{
private:
    string name; 
    string year; 
    list<Employee ?> e;
}

what is the difference between :

list<Employee *> e  
list<Employee &> e

and how do i implement the destructor ~Movie() for each variation ?

One compiles, one doesn't, and neither should actually be used. — T.C., Dec 08 '15 at 18:35

score 2 · Answer 1 · answered Dec 08 '15 at 18:41

2

You cannot have a list of references list<Employee &> e because the elements in the list have to be Assignable and a reference cannot be assigned to.

answered Dec 08 '15 at 18:41

russoue

5,180
5
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101010 · Accepted Answer · 2015-12-08T18:52:03.827

You can't have an STL container of references to objects. That is,

std::list<Employee&> e;

doesn't have a chance to compile. This is attributed to the fact that STL containers require that their elements are Erasable [Note: Before C++11 the requirements were to be CopyAssignable and CopyConstructible]. Unfortunately, references are not.

Also since you have the C++11 tag, you should be aware that use of raw pointers is highly discouraged in favour of smart pointers like std::unique_ptr and std::shared_ptr. Thus, is better to avoid this:

std::list<Employee*> e;

in favour of something like:

std::list<std::shared_ptr<Employee>> e;

score 0 · Answer 3 · answered Dec 08 '15 at 18:44

0

As stated in the comments list<Employee &> e won't compile. If you want to do a reference to the class and not a pointer, you can use list<std::reference_wrapper<Employee>> e. The type has to be Assignable.

answered Dec 08 '15 at 18:44

mculp

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1
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3 Answers3