std::make_shared
| 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.
Contents |
[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 contructor of T. If an exception is thrown, this function has no effect.
[edit] Notes
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.
Moreover, f(shared_ptr<int>(new int(42)), g()) can lead to memory leak if g throws an exception. This problem doesn't exist if make_shared is used.
[edit] Example
#include <iostream> #include <memory> void foo(std::shared_ptr<int> i) { (*i)++; } int main() { auto sp = std::make_shared<int>(10); foo(sp); std::cout << *sp << std::endl; }
Output:
11
[edit] See also
constructs new shared_ptr (public member function) |
|
| creates a shared pointer that manages a new object allocated using an allocator (function template) |
|