std::experi...::operator[](3)

💅 std::experi...::operator[](3)

okay so bestie, welcome to the C++ Standard Library corner of the manual — section 3, no less — and today's main character is std::experimental::simd::operator[]. yes the title's got that little experi... ellipsis thing going on, that's just how it's filed, don't come for her 🎀

✨ NAME ✨

std::experimental::simd::operator[] — literally std::experimental::simd::operator[], that's the whole name, we love a self-titled icon 👑

🦋 Synopsis 🦋

reference operator[]( std::size_t i );        (1) (parallelism TS v2)
value_type operator[]( std::size_t i ) const; (2) (parallelism TS v2)

so these subscript operators are the whole vibe — they let you read and write single elements of a simd. like, one element at a time, slay 🫶

• (1) — returns a reference proxy to the i-th element. and listen, this is important: this proxy type should not be captured into an lvalue. lvalues of simd::reference can only convert to value_type. meanwhile rvalues of simd::reference overload assignment and all compound assignment operators as well as swap. iykyk 💅
• (2) — returns a prvalue of the i-th element. and here's the tea: in contrast to containers, which contain objects of type value_type, a simd is not a container of individual objects, and therefore cannot return an lvalue-reference. it's giving "different genre of data structure entirely" and honestly? respect ✨

🌸 Parameters 🌸

• i — the element index. required to be less than size(). that's the rule, don't push it 🔥

💖 Example 💖

// Run this code

#include <cstddef>
#include <cstdint>
#include <experimental/simd>
#include <iostream>
namespace stdx = std::experimental;

int main()
{
    const stdx::native_simd<std::int64_t> a = 3;
    for (std::size_t i = 0; i != a.size(); ++i)
        std::cout << a[i] << ' ';
    std::cout << '\n';
}

⭐ Possible output: ⭐

3 3 3 3 3 3 3 3

eight threes. she ate and left no crumbs 😭💀

small reminder bestie: i has to be less than size(), and please don't capture that reference proxy into an lvalue. i'm not being dramatic, the standard said it, not me 💜

and that's the page!! source: it's from http://cppreference.com, dated 2024.06.10, and it lives at std::experi...::operator[](3) — go forth and index your simd elements responsibly, mwah 🧚💖🎀