< cpp‎ | memory‎ | shared ptr
Dynamic memory management
Uninitialized storage
(deprecated since c++17)
(deprecated since c++17)
(deprecated since c++17)
Garbage collection support
C Library
Low level memory management
Defined in header <memory>
template< class T, class... Args >
shared_ptr<T> make_shared( 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 T.


[edit] Parameters

args - list of arguments with which an instance of T will be constructed.

[edit] Return value

std::shared_ptr of an instance of type T.

[edit] Exceptions

May throw std::bad_alloc or any exception thrown by the constructor of T. If an exception is thrown, this function has no effect.

[edit] Notes

This function is typically used to replace the construction std::shared_ptr<T>(new T(args...)) of a shared pointer from the raw pointer returned by a call to new. In contrast to that expression, std::make_shared<T> typically allocates memory for the T object and for the std::shared_ptr's control block with a single memory allocation (this is a non-binding requirement in the Standard), where std::shared_ptr<T>(new T(args...)) performs at least two memory allocations.

Moreover, code such as f(std::shared_ptr<int>(new int(42)), g()) can cause a memory leak if g throws an exception because g() may be called after new int(42) and before the constructor of shared_ptr<int>. This doesn't occur in f(std::make_shared<int>(42), g()), since two function calls are never interleaved.

[edit] Example

#include <iostream>
#include <memory>
void foo(const std::shared_ptr<int>& i)
int main()
    auto sp = std::make_shared<int>(12);
    std::cout << *sp << std::endl;



[edit] See also

constructs new shared_ptr
(public member function) [edit]
creates a shared pointer that manages a new object allocated using an allocator
(function template) [edit]
creates a unique pointer that manages a new object
(function template) [edit]