std::tuple_size<std::tuple>
Defined in header <tuple> |
||
|---|---|---|
|
(since C++11) |
Provides access to the number of elements in a tuple as a compile-time constant expression.
Helper variable template
|
(since C++17) |
Inherited from std::integral_constant
Member constants
|
value
[static]
|
sizeof...(Types) (public static member constant) |
Member functions
|
operator std::size_t
|
converts the object to std::size_t, returns value (public member function) |
|
operator()
(C++14)
|
returns value (public member function) |
Member types
| Type | Definition |
|---|---|
value_type |
std::size_t |
type |
std::integral_constant<std::size_t, value> |
Example
#include <iostream>
#include <tuple>
template <class T>
void test(T value)
{
int a[std::tuple_size_v<T>]; // can be used at compile time
std::cout << std::tuple_size<T>{} << ' ' // or at run time
<< sizeof a << ' '
<< sizeof value << '\n';
}
int main()
{
test(std::make_tuple(1, 2, 3.14));
}Possible output:
3 12 16See also
| Structured binding (C++17) | binds the specified names to sub-objects or tuple elements of the initializer |
|
(C++11)
|
obtains the number of elements of a tuple-like type (class template) |
|
(C++11)
|
obtains the size of a pair (class template specialization) |
|
(C++11)
|
obtains the size of an array (class template specialization) |
|
(C++20)
|
obtains the number of components of a std::ranges::subrange (class template specialization) |
|
(C++11)
|
tuple accesses specified element (function template) |
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