Home Original page

deduction guides for std::tuple - cppreference.com

From cppreference.com

Defined in header <tuple>

template<class... UTypes> tuple(UTypes...) -> tuple<UTypes...>;

 (1) (since C++17)

template<class T1, class T2> tuple(std::pair<T1, T2>) -> tuple<T1, T2>;

 (2) (since C++17)

template<class Alloc, class... UTypes> tuple(std::allocator_arg_t, Alloc, UTypes...) -> tuple<UTypes...>;

 (3) (since C++17)

template<class Alloc, class T1, class T2> tuple(std::allocator_arg_t, Alloc, std::pair<T1, T2>) -> tuple<T1, T2>;

 (4) (since C++17)

template<class Alloc, class... UTypes> tuple(std::allocator_arg_t, Alloc, tuple<UTypes...>) -> tuple<UTypes...>;

 (5) (since C++17)

These deduction guides are provided for std::tuple to account for the edge cases missed by the implicit deduction guides, in particular, non-copyable arguments and array to pointer conversion.

Example

#include <tuple>
int main()
{
    int a[2], b[3], c[4];
    std::tuple t1{a, b, c}; // explicit deduction guide is used in this case
}