std::tuple

 

C++

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Utilities library

Type support (basic types, RTTI, type traits)

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Relational operators

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

Pairs and tuples

pair

tuple (C++11)

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piecewise_construct (C++11)

Swap, forward and move

swap

forward (C++11)

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declval (C++11)

 

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 > class tuple;		(since C++11)

Class template std::tuple is a fixed-size collection of heterogeneous values. It is a generalization of std::pair.

Template parameters

Types...

-

the types of the elements that the tuple stores. Empty list is supported.

Member functions

(constructor)	constructs a new tuple (public member function)
operator=	assigns the contents of one tuple to another (public member function)
swap	swaps the contents of two tuples (public member function)

Non-member functions

make_tuple	creates a tuple object of the type defined by the argument types (function template)
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)
std::get(std::tuple)	tuple accesses specified element (function template)
operator==operator!=operator<operator<=operator>operator>=	lexicographically compares the values in the tuple (function template)
std::swap(std::tuple) (C++11)	specializes the std::swap algorithm (function template)

Helper classes

tuple_size	obtains the size of tuple at compile time (class template specialization)
tuple_element	obtains the type of the specified element (class template specialization)
std::uses_allocator<std::tuple> (C++11)	specializes the std::uses_allocator type trait (class template specialization)
ignore	placeholder to skip an element when unpacking a tuple using tie (constant)

Example

Run this code

#include <tuple>
#include <iostream>
#include <string>
#include <stdexcept>
 
std::tuple<double, char, std::string> get_student(int id)
{
    if (id == 0) return std::make_tuple(3.8, 'A', "Lisa Simpson");
    if (id == 1) return std::make_tuple(2.9, 'C', "Milhouse Van Houten");
    if (id == 2) return std::make_tuple(1.7, 'D', "Ralph Wiggum");
    throw std::invalid_argument("id");
}
 
int main()
{
    auto student0 = get_student(0);
    std::cout << "ID: 0, "
              << "GPA: " << std::get<0>(student0) << ", "
              << "grade: " << std::get<1>(student0) << ", "
              << "name: " << std::get<2>(student0) << '\n';
 
    double gpa1;
    char grade1;
    std::string name1;
    std::tie(gpa1, grade1, name1) = get_student(1);
    std::cout << "ID: 1, "
              << "GPA: " << gpa1 << ", "
              << "grade: " << grade1 << ", "
              << "name: " << name1 << '\n';
}

Output:

ID: 0, GPA: 3.8, grade: A, name: Lisa Simpson
ID: 1, GPA: 2.9, grade: C, name: Milhouse Van Houten

References

• C++11 standard (ISO/IEC 14882:2011):

• 20.4 Tuples [tuple]