std::meta::rank
From cppreference.com
| Defined in header <meta>
|
||
consteval std::size_t rank( std::meta::info r );
|
(since C++26) | |
Returns the number of dimensions of reflected array type represented by reflection r.
Equivalent to return std::rank<T>::value, where T is the type represented by std::meta::dealias(r).
Parameters
| r | - | a reflection value |
Return value
The number of dimensions of the array.
Exceptions
Throws std::meta::exception if r does not represent an array type.
Example
Run this code
#include <meta>
#include <print>
static_assert(std::meta::rank(^^int) == 0);
static_assert(std::meta::rank(^^int[5]) == 1);
static_assert(std::meta::rank(^^int[5][5]) == 2);
static_assert(std::meta::rank(^^int[][5][5]) == 3);
int main()
{
int a[][3]{{1, 2, 3}};
std::println("{}", a);
// The rank of reference type, e.g., a[0], that is int(&)[3], is 0:
static_assert(std::meta::rank(^^decltype(a[0])) == 0);
static_assert(std::meta::is_same_type(^^decltype(a[0]), ^^int(&)[3]));
// The solution is to remove the reference type.
static_assert(std::meta::rank(std::meta::remove_cvref(^^decltype(a[0]))) == 1);
}
Output:
[[1, 2, 3]]