std::make_tuple

 

C++

Language

Standard library headers

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Utilities library

Strings library

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Algorithms library

Iterators library

Numerics library

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Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

Error handling

Program utilities

Variadic functions

Date and time

Function objects

initializer_list (C++11)

bitset

hash (C++11)

Relational operators

rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

Pairs and tuples

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

integer_sequence (C++14)

Swap, forward and move

swap

exchange (C++14)

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

Type operations

declval (C++11)

as_const (C++17)

 

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

Helper classes

tuple_size

tuple_element

uses_allocator

ignore

 

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&.

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 special_decay { using type = typename std::decay<T>::type; };   template <class T> struct special_decay<std::reference_wrapper<T>> { using type = T&; };   template <class T> using special_decay_t = typename special_decay<T>::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 t1 is (10, Test, 3.14, 7, 1)
5 7

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)