std::extents,std::dextents(3)

🌸 NAME 🌸

Okay bestie, welcome to the std::extents,std::dextents(3) page from the C++ Standard Libary manual — yes, that's the spelling in the header, we're keeping it 💀. This whole page is about std::extents and std::dextents, and that's literally the name. No cap.

---

✨ Synopsis ✨

Defined in header <mdspan>:

template< class IndexType, std::size_t... Extents > (1) (since C++23)
class extents;
template< class IndexType, std::size_t Rank >       (2) (since C++23)
using dextents = /* see below */

1. Represents a multidimensional index space of rank equal to sizeof...(Extents).
2. A convenient alias template for an all-dynamic extents. Let d denote std::dynamic_extent, each specialization of it dextents<IndexType, Rank> is equivalent to extents<IndexType /*, d, d, ..., d*/> (i.e. d is repeated a total of Rank times).

Each specialization of extents models regular and is TriviallyCopyable. Periodt. 💅

---

🎀 Template parameters 🎀

• IndexType — the type of each non-dynamic Extents. Shall be a signed or unsigned integer type. Otherwise, the program is ill-formed.
• Extents — represents extent (size of an integer interval) for each rank index. Each element of it is either equal to std::dynamic_extent (in this case, it represents a dynamic extent and the extent size will be determined dynamically), or is representable as a value of type IndexType (then it represents a static extent and the extent size is just the value of it), or else the program is ill-formed.
• Rank — denotes the rank of an all-dynamic extents.

---

🦋 Member types 🦋

• index_type — IndexType
• size_type — std::make_unsigned_t<index_type>
• rank_type — std::size_t

---

💅 Member objects 💅

• dynamic-extents (private) — an array of type std::array<index_type, rank_dynamic()>, which stores the size of each dynamic extents. (exposition-only member object*)

---

💖 Member functions 💖

• constructor — constructs an extents (public member function)

⭐ Observers ⭐

• rank [static] — returns the static rank of an extents (public static member function)
• rank_dynamic [static] — returns the dynamic rank of an extents (public static member function)
• static_extent [static] — returns static extent size of an extents at a certain rank index (public static member function)
• extent — returns dynamic extent size of an extents at a certain rank index (public member function)

🧚 Helpers 🧚

• fwd-prod-of-extents — returns the product of extent size in range [0, i) (exposition-only member function*)
• rev-prod-of-extents — returns the product of extents size in range [i + 1, rank()) (exposition-only member function*)
• index-cast — casts the input into an integer type (exposition-only member function*)
• dynamic-index (private) — returns the number of dynamic extents below a certain rank index (exposition-only member function*)
• dynamic-index-inv (private) — returns the number r such that in range [0, r + 1) there is exactly i + 1 dynamic extents for a certain argument i (exposition-only member function*)

---

🔥 Non-member functions 🔥

• operator== (C++23) — compare underlying extents in each dimension of two extents (function)

🌈 Deduction guides(C++23) 🌈

This one is just listed on the page as Deduction guides(C++23) — no extra details here, bestie. That's the whole vibe check. 💀

---

🍓 Example 🍓

This section is incomplete Reason: no example

---

👑 See also 👑

• rank (C++11) — obtains the number of dimensions of an array type (class template)
• extent (C++11) — obtains the size of an array type along a specified dimension (class template)

---

💜 Category 💜

• Todo no example

---

Source/version/date sign-off: http://cppreference.com · 2024.06.10 · std::extents,std::dextents(3) — love u, bye bestie 💖✨