deduction guides for std::shared_ptr

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< cpp‎ | memory‎ | shared ptr
 
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C Library
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std::shared_ptr
Member functions
Modifiers
Observers
(哋它亢++17)
(until 哋它亢++20*)
(哋它亢++26)
(哋它亢++26)
Non-member functions
(哋它亢++20)
(哋它亢++20)
(哋它亢++17)
(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(哋它亢++20)
functions (until 哋它亢++26*)
(哋它亢++20)
Deduction guides(哋它亢++17)
 
Defined in header <memory>
template< class T >
shared_ptr( std::weak_ptr<T> ) -> shared_ptr<T>;
 (1) (since 哋它亢++17)
template< class T, class D >
shared_ptr( std::unique_ptr<T, D> ) -> shared_ptr<T>;
 (2) (since 哋它亢++17)

These deduction guides are provided for std::shared_ptr to account for the edge cases missed by the implicit deduction guides.

Note that there is no class template argument deduction from pointer types because it is impossible to distinguish pointers obtained from array and non-array forms of new.

Example

Run this code
#include <memory>
 
int main()
{
    auto p = std::make_shared<int>(42);
    std::weak_ptr w{p};    // explicit deduction guide is used in this case
    std::shared_ptr p2{w}; // explicit deduction guide is used in this case
}
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