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Reference

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<memory>

classes
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  allocator_arg_t
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  make_shared
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objects
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  allocator_arg

Reference
<memory>
allocate_shared

function template

std::allocate_shared

template <class T, class Alloc, class... Args>  shared_ptr<T> allocate_shared (const Alloc& alloc, Args&&... args);

Allocate shared_ptr

Allocates memory for an object of type T using alloc and constructs it passing args to its constructor. The function returns an object of type shared_ptr<T> that owns and stores a pointer to the constructed object (with a use count of 1).

This function uses alloc to allocate storage for the object. A similar function, make_shared uses ::new to allocate the storage instead.

Parameters

alloc: An allocator object.
Alloc is a type for which allocator_traits is well defined.
args: List of elements passed to T's constructor.
Args is a list of zero or more types.

Return Value

A shared_ptr object that owns and stores a pointer to a newly allocated object of type T.

Example

// allocate_shared example
#include <iostream>
#include <memory>

int main () {
  std::allocator<int> alloc;    // the default allocator for int
  std::default_delete<int> del; // the default deleter for int

  std::shared_ptr<int> foo = std::allocate_shared<int> (alloc,10);

  auto bar = std::allocate_shared<int> (alloc,20);

  auto baz = std::allocate_shared<std::pair<int,int>> (alloc,30,40);

  std::cout << "*foo: " << *foo << '\n';
  std::cout << "*bar: " << *bar << '\n';
  std::cout << "*baz: " << baz->first << ' ' << baz->second << '\n';

  return 0;
}

Output:

*foo: 10
*bar: 20
*baz: 30 40

classes

enum classes

functions

objects

std::allocate_shared

Parameters

Return Value

Example

See also