std::tuple

Learn heterogeneous collections with std::tuple.

std::tuple

std::tuple is a template that holds N values of different types in one container. The syntax is std::tuple<int, double, std::string> t{42, 3.14, "hello"};. Each element may have a different type; this generalizes std::pair.

Elements are accessed with std::get<index>(t). The index must be known at compile time; it does not change at run time. std::tuple_size and std::tuple_element give size and type info. Tuples are common for returning multiple values from a function.

Access with std::get

std::get reads a tuple element by a compile-time index. std::get<0>(t) returns the first element, std::get<1>(t) the second. A type also works: std::get<int>(t) returns the int element of the tuple.

An out-of-range index errors at compile time. If the same type appears more than once, type-based access is ambiguous; use an index instead. Tuples can also be unpacked with structured bindings: auto [a, b] = t; binds each element to a separate variable.

Exercise Build a tuple and print

Create std::tuple<int, double, std::string> t{42, 3.14, "hello"};. Read the first element with std::get<0>(t) and print it via std::cout. Remember to include <tuple>.

Show example solution

#include <iostream>
#include <tuple>
#include <string>

int main() {
    std::tuple<int, double, std::string> t{42, 3.14, "hello"};
    std::cout << std::get<0>(t);
    return 0;
}

Test yourself

Complete the std::get line

std::tuple<int, double> t{42, 3.14};
auto x = ____;

Show answer

std::tuple<int, double> t{42, 3.14};
auto x = std::get<0>(t);

What does std::tuple hold?
- Only two values
- N values of the same type
- N values of different types
- Only pointers
Show answer

N values of different types — std::tuple holds N values of different types.
Match each tool to its purpose

std::tuple<T1, T2>

Heterogeneous container
std::get<0>(t)

Read first element
std::tuple_size<t>

Element count
auto [a, b] = t

Structured bindings

Next lesson: Summary - Variadic templates

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