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# std::make_tuple

From cppreference.com
< cpp‎ | utility‎ | tuple

Defined in header `<tuple>` |  |
template< class... Types > tuple<VTypes...> make_tuple( Types&&... args ); |  | (since C++11) (until C++14)
template< class... Types > constexpr tuple<VTypes...> make_tuple( Types&&... args ); |  | (since C++14)

Creates a tuple object, deducing the target type from the types of arguments.

For each `Ti` in `Types...`, the corresponding type `Vi` in `Vtypes...` is std::decay<Ti>::type unless application of std::decay results in std::reference_wrapper<X> for some type `X`, in which case the deduced type is `X&`.

### [edit] Parameters

args | - | zero or more arguments to construct the tuple from

### [edit] Return value

A std::tuple object containing the given values, created as if by std::tuple<VTypes...>(std::forward<Types>(t)...).

### [edit] Possible implementation

    template <class T>
    struct unwrap_refwrapper
    {
        using type = T;
    };

    template <class T>
    struct unwrap_refwrapper<std::reference_wrapper<T>>
    {
        using type = T&;
    };

    template <class T>
    using special_decay_t = typename unwrap_refwrapper<typename std::decay<T>::type>::type;

    template <class... Types>
    auto make_tuple(Types&&... args)
    {
        return std::tuple<special_decay_t<Types>...>(std::forward<Types>(args)...);
    }

### [edit] Example

Run this code

    #include <iostream>
    #include <tuple>
    #include <functional>

    std::tuple<int, int> f() // this function returns multiple values
    {
        int x = 5;
        return std::make_tuple(x, 7); // return {x,7}; in C++17
    }

    int main()
    {
        // heterogeneous tuple construction
        int n = 1;
        auto t = std::make_tuple(10, "Test", 3.14, std::ref(n), n);
        n = 7;
        std::cout << "The value of t is "  << "("
                  << std::get<0>(t) << ", " << std::get<1>(t) << ", "
                  << std::get<2>(t) << ", " << std::get<3>(t) << ", "
                  << std::get<4>(t) << ")\n";

        // function returning multiple values
        int a, b;
        std::tie(a, b) = f();
        std::cout << a << " " << b << "\n";
    }

Output:

    The value of t is (10, Test, 3.14, 7, 1)
    5 7

### [edit] See also

tie | creates a `tuple` of lvalue references or unpacks a tuple into individual objects (function template) [edit]
forward_as_tuple | creates a `tuple` of rvalue references (function template) [edit]
tuple_cat | creates a `tuple` by concatenating any number of tuples (function template) [edit]
apply (C++17) | calls a function with a tuple of arguments (function template) [edit]

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