Defined in header <memory>
template< class T, class Alloc, class... Args >
shared_ptr<T> allocate_shared( const Alloc& alloc, Args... args );
Constructs an object of type
T and wraps it in a std::shared_ptr using
args as the parameter list for the constructor of
All memory allocation is done using a copy of alloc, which satisfies the
Allocator requirements. The copy constructor and the destructor of
Alloc must not throw exceptions.
|alloc||-|| The |
|args...||-|| list of arguments with which an instance of |
 Return value
std::shared_ptr of an instance of type
Can throw the exceptions thrown from Alloc::allocate() or from the constructor of
T. If an exception is thrown, this function has no effect.
This function typically allocates memory for the T object and for the shared_ptr's control block with a single memory allocation (it is a non-binding requirement in the Standard). In contrast, the declaration
std::shared_ptr<T> p(new T(Args...)) performs at least two memory allocations, which may incur unnecessary overhead.
A copy of
alloc is stored as part of the control block so that it can be used to deallocate it once both shared and weak reference counts reach zero.
 See also
| constructs new |
(public member function)
| creates a shared pointer that manages a new object |