std::flat_set::find(3)

Okay bestie, this is std::flat_set::find(3) from the C++ Standard Libary — yes, that manual name, folded in right here at the top. 💅 This whole page is literally about std::flat_set::find, and it's giving “I will locate your element” main character energy. No cap. ✨

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💖 NAME 💖

std::flat_set::find — and yeah, the name is std::flat_set::find. The original said it twice, so it's double-confirmed. Periodt. 🎀

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🎀 Synopsis 🎀

Okay so here are the signatures, bestie — all of them are since C++23, not me making that up:

          iterator find( const Key& key );             (1) (since C++23)
          const_iterator find( const Key& key ) const; (2) (since C++23)
          template< class K >                          (3) (since C++23)
          iterator find( const K& x );
          template< class K >                          (4) (since C++23)
          const_iterator find( const K& x ) const;

1. Overloads (1) and (2) — finds an element with key equivalent to key. 🔍
2. Overloads (3) and (4) — finds an element with key that compares equivalent to the value x. This overload participates in overload resolution only if the qualified-id Compare::is_transparent is valid and denotes a type. It allows calling this function without constructing an instance of Key. 🦋

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🧚 Parameters 🧚

• key — key value of the element to search for. 💖
• x — a value of any type that can be transparently compared with a key. 🌸

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⭐ Return value ⭐

An iterator to the requested element. If no such element is found, past-the-end (see end()) iterator is returned. That's the whole vibe — found means iterator, not found means past-the-end. 😭

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🔥 Complexity 🔥

Logarithmic in the size of the container. So yeah, it's not doing a whole linear scroll through the group chat. 💅

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🌈 Example 🌈

Run this code, bestie — it's a whole demo:

       // Run this code

        #include <iostream>
        #include <flat_set>

        struct LightKey
        {
            int x;
        };

        struct FatKey
        {
            int x;
            int data[1000]; // a heavy blob
        };

        // As detailed above, the container must use std::less<> (or other
       transparent
        // Comparator) to access these overloads. This includes standard
       overloads,
        // such as comparison between std::string and std::string_view.
        bool operator<(const FatKey& fk, const LightKey& lk) { return fk.x <
       lk.x; }
        bool operator<(const LightKey& lk, const FatKey& fk) { return lk.x <
       fk.x; }
        bool operator<(const FatKey& fk1, const FatKey& fk2) { return fk1.x <
       fk2.x; }

        int main()
        {
            // Simple comparison demo.
            std::flat_set<int> example{1, 2, 3, 4};

            if (auto search = example.find(2); search != example.end())
                std::cout << "Found " << (*search) << '\n';
            else
                std::cout << "Not found\n";

            // Transparent comparison demo.
            std::flat_set<FatKey, std::less<>> example2{{1, {}}, {2, {}}, {3,
       {}}, {4, {}}};

            LightKey lk = {2};
            if (auto search = example2.find(lk); search != example2.end())
                std::cout << "Found " << search->x << '\n';
            else
                std::cout << "Not found\n";
        }

Output:

        Found 2
        Found 2

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👑 See also 👑

• count — returns the number of elements matching specific key (public member function). 🍓
• equal_range — returns range of elements matching a specific key (public member function). 💜

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Cute sign-off time: source is http://cppreference.com, version 2024.06.10, and this iconic page is std::flat_set::find(3) — bye bestie, go find your element 💖🦋💅