CODEWITHSUNDEEP
c++
Andrew Martin
Andrew Martin

Reputation: 303

Heap-allocated object constructors

Suppose I need to create a heap allocated container from another container. Does the initial container need to be also heap-allocated, or are its values implicitly copied into the heap, and hence the original container can just be a local variable? Example:

list<int> my_function()
{
    set<int> my_set;
    my_set.insert(1);
    my_set.insert(2);

    list<int> *my_list = new list<int>(my_set.begin(), my_set.end());

    return *my_list;
}

versus

list<int> my_function()
{
    set<int> *my_set = new set<int>;
    my_set->insert(1);
    my_set->insert(2);

    list<int> *my_list = new list<int>(my_set->begin(), my_set->end());

    return *my_list;
}

Which of the above is correct? I want to avoid duplicating heap-memory without my knowledge, of course.

Upvotes: 0

Views: 614

Answers (1)

Danvil
Danvil

Reputation: 22991

This would be correct:

list<int> my_function()
{
    set<int> my_set;
    my_set.insert(1);
    my_set.insert(2);   
    return list<int>(my_set.begin(), my_set.end());
}

I am not sure what you mean with "heap allocated", but keep in mind, that list and set already store data on the heap.

Upvotes: 2

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