std::unorde...:equal_range(3)

💖 NAME

okay so welcome to the C++ Standard Library manual, bestie — this page is all about std::unordered_set::equal_range. The NAME line is literally:

std::unordered_set::equal_range - std::unordered_set::equal_range

and yeah, it said what it said twice. iconique. 💅

---

🌸 Synopsis

Here are the overloads exactly as the page lays them out — line wraps and all, don't come for me:

std::pair<iterator, iterator> equal_range( const Key& key );
(1) (since C++11)
std::pair<const_iterator, const_iterator> equal_range( const Key&
(2) (since C++11)
key ) const;
template< class K >
(3) (since C++20)
std::pair<iterator, iterator> equal_range( const K& x );
template< class K >
std::pair<const_iterator, const_iterator> equal_range( const K& x
(4) (since C++20)
) const;

So what's the tea? 🫖

Overloads 1,2) return a range containing all elements with key key in the container. That range is defined by two iterators: the first points to the first element of the wanted range, and the second points past the last element of the range. classic iterator duo energy ✨

Overloads 3,4) return a range containing all elements in the container with key equivalent to x. This overload participates in overload resolution only if Hash::is_transparent and KeyEqual::is_transparent are valid and each denotes a type. It assumes that such a Hash is callable with both K and Key type, and that the KeyEqual is transparent, which, together, allows calling this function without constructing an instance of Key. no cap, that's the whole transparency moment 🦋

---

✨ Parameters

• key — key value to compare the elements to.
• x — a value of any type that can be transparently compared with a key.

---

🎀 Return value

A std::pair containing a pair of iterators defining the wanted range. If there are no such elements, past-the-end (see end()) iterators are returned as both elements of the pair. so you get a little "nothing here" signal, not a whole crisis 😌

---

🔥 Complexity

Average case: linear in the number of elements with the key key. Worst case: linear in the size of the container. fr fr, know the difference 💀

---

🦋 Notes

The page drops a feature-test macro table. Here's the whole vibe:

• Feature-test macro: __cpp_lib_generic_unordered_lookup
• Value: 201811L
• Std: (C++20)
• Feature: Heterogeneous comparison lookup in unordered associative containers, overloads (3,4)

---

🍓 Example

This section is incomplete. Reason: no example. 💀

the audacity, honestly.

---

👑 See also

• find — finds element with specific key (public member function)
• contains — checks if the container contains element with specific key (C++20) (public member function)
• count — returns the number of elements matching specific key (public member function)
• equal_range — returns range of elements matching a specific key (function template)

---

🏷️ Category

• * Todo no example

---

Source/version: http://cppreference.com · date: 2024.06.10 · page vibe: std::unorde...:equal_range(3) — okay bye bestie, go get that range 💖✨