std::make_tuple

C++

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std::tuple

Member functions

tuple::tuple

tuple::operator=

tuple::swap

Non-member functions

make_tuple

tie

forward_as_tuple

tuple_cat

operator==operator!=operator<operator<=operator>operator>=

std::swap

get

Deduction guides(C++17)

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tuple_size

tuple_element

uses_allocator

ignore

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

Parameters

args

-

zero or more arguments to construct the tuple from

Return value

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

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)...); }

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

See also

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