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c++boostshared-ptrsmart-pointersmake-shared

Allocate char* array with boost::make_shared

To allocate a char* array I would normally write something like:

char* arr = new char[size];

How can I achieve the same thing using boost::shared_ptr (or probably boost::shared_array) and boost::make_shared?

My guesses are:

1) boost::shared_ptr<char[]> arr = boost::make_shared<char[]>(size);

2) boost::shared_ptr<char> arr = boost::make_shared<char>(size);

3) boost::shared_ptr<char> arr = boost::shared_ptr<char>(new char[size]);

The last one looks right but is it guaranteed that upon destruction delete [] arr will be called?

Solution

  • The correct one is make_shared<T[]>(n).

    Bear in mind that pre-c++20 it's an extension not present in the standard library (although unique_ptr<T[]> is part of the standard).

    Boost's shared_ptr will indeed call the correct deleter (naively, delete[]) for it.