std::flat_set::erase(3)

💖 NAME 💖

std::flat_set::erase — that's the whole name, bestie, and yes it's from the C++ Standard Library manual for std::flat_set::erase(3) 💅

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✨ Synopsis ✨

   iterator erase( iterator position );                         (1)
(since C++23)
   iterator erase( const_iterator pos );                        (2)
(since C++23)
   iterator erase( const_iterator first, const_iterator last ); (3)
(since C++23)
   size_type erase( const Key& key );                           (4)
(since C++23)
   template< class K >                                          (5)
(since C++23)
   size_type erase( K&& x );

It removes specified elements from the container ✨

1. 1,2) Removes the element at pos.
2. 3) Removes the elements in the range [first, last), which must be a valid range in *this.
3. 4) Removes the element (if one exists) with the key equivalent to key.
4. 5) Removes all elements 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, and neither iterator nor const_iterator is implicitly convertible from K. It allows calling this function without constructing an instance of Key.

Information on iterator invalidation is copied from here.

The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos. 🚨

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🌈 Parameters 🌈

• pos — iterator to the element to remove
• first, last — range of elements to remove
• key — key value of the elements to remove
• x — a value of any type that can be transparently compared with a key denoting the elements to remove

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🎀 Return value 🎀

• 1-3) Iterator following the last removed element.
• 4) Number of elements removed (0 or 1).
• 5) Number of elements removed.

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🦋 Exceptions 🦋

• 1-3) Throws nothing.
• 4,5) Any exceptions thrown by the Compare object.

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🔥 Complexity 🔥

Depends on underlying container. Typically linear.

This section is incomplete Reason: revision required

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🌸 Example 🌸

// Run this code 👇

#include <flat_set>
#include <iostream>

int main()
{
    std::flat_set<int> c = {1, 2, 3, 4, 1, 2, 3, 4};

    auto print = [&c]
    {
        std::cout << "c = { ";
        for (int n : c)
            std::cout << n << ' ';
        std::cout << "}\n";
    };
    print();

    std::cout << "Erase all odd numbers:\n";
    for (auto it = c.begin(); it != c.end();)
    {
        if (*it % 2 != 0)
            it = c.erase(it);
        else
            ++it;
    }
    print();

    std::cout << "Erase 1, erased count: " << c.erase(1) << '\n';
    std::cout << "Erase 2, erased count: " << c.erase(2) << '\n';
    std::cout << "Erase 2, erased count: " << c.erase(2) << '\n';
    print();
}

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👑 See also 👑

• clear — clears the contents (public member function)

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🧚 Category 🧚

• Todo with reason

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source/version: http://cppreference.com, date 2024.06.10, page std::flat_set::erase(3) — that's the whole manual page, bestie! bye bye 🫶💖