std::seed_seq::seed_seq(3)

💖 std::seed_seq::seed_seq(3) 💖

okay so this is the constructor page for std::seed_seq, straight from the C++ Standard Libary manual (yes, that's how the header spells it — their typo, not mine 💅). It's giving tiny-but-important seed energy, and we're keeping every single detail exactly where it belongs. Obsessed, honestly.

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🌸 NAME 🌸

std::seed_seq::seed_seq — the constructor for std::seed_seq itself. The page literally says std::seed_seq::seed_seq - std::seed_seq::seed_seq, and that self-reference is iconic. Periodt.

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✨ Synopsis ✨

seed_seq() noexcept;                     (1) (since C++11)
seed_seq( const seed_seq& ) = delete;    (2) (since C++11)
template< class InputIt >                (3) (since C++11)
seed_seq( InputIt begin, InputIt end );
template< class T >                      (4) (since C++11)
seed_seq( std::initializer_list<T> il );

1. The default constructor creates a std::seed_seq object with an initial seed sequence of length zero. Empty. Blank. A fresh start, no cap.
2. The copy constructor is deleted: std::seed_seq is not copyable. You cannot duplicate this icon, bestie.
3. Constructs a std::seed_seq with the initial seed sequence obtained by iterating over the range [begin, end) and copying the values obtained by dereferencing the iterator, modulo 232 — and the page clarifies that this means the lower 32 bits are copied.
4. Equivalent to seed_seq(il.begin(), il.end()). This constructor enables list-initialization from the list of seed values. This overload participates in overload resolution only if T is an integer type. Integer besties only, iykyk.

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🎀 Parameters 🎀

• begin, end — the initial seed sequence represented as a pair of input iterators whose std::iterator_traits<>::value_type is an integer type. That's the range vibe.
• il — a std::initializer_list of objects of integer type, providing the initial seed sequence. The list is the moment.

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🦋 Type requirements 🦋

• InputIt must meet the requirements of LegacyInputIterator. That's the vibe check it has to pass.

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💅 Exceptions 💅

• 3,4) — throws std::bad_alloc on allocation failure. Allocation said nope? You get std::bad_alloc.

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🌈 Example 🌈

// Run this code

        #include <iterator>
        #include <random>
        #include <sstream>

        int main()
        {
            std::seed_seq s1; // default-constructible
            std::seed_seq s2{1, 2, 3}; // can use list-initialization
            std::seed_seq s3 = {-1, 0, 1}; // another form of list-
       initialization
            int a[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
            std::seed_seq s4(a, a + 10); // can use iterators
            std::istringstream buf("1 2 3 4 5");
            std::istream_iterator<int> beg(buf), end;
            std::seed_seq s5(beg, end); // even stream input iterators
        }

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👑 Defect reports 👑

The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Yes, the standard got a little glow-up after the fact.

• DR: LWG 3422 — Applied to: C++11
  • Behavior as published: the default constructor never fails but might be not noexcept; the initializer list constructor disabled list-initialization from iterator pairs
  • Correct behavior: made noexcept; constrained

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mwah 💋 this page is from the C++ Standard Libary manual, source http://cppreference.com, dated 2024.06.10. That's the whole footer folded into a cute lil' sign-off, bestie. slay 🫶