std::flat_map::erase(3)

💅 std::flat_map::erase(3) 💅

okay so bestie, welcome to the std::flat_map::erase page from the C++ Standard Libary manual — section 3, no cap. It's giving erase energy, and every overload here is since C++23. Let's get into it 💖

✨ NAME ✨

std::flat_map::erase — std::flat_map::erase (yes bestie, the name is the name 😭).

📜 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 );

okay so what it does: removes specified elements from the container. iconic.

• 1,2) Removes the element at pos.
• 3) Removes the elements in the range [first, last), which must be a valid range in *this.
• 4) Removes the element (if one exists) with the key equivalent to key.
• 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 — periodt.

⚠️ bestie, listen: 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. no cap, that's a real warning.

🌸 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.

🫶 Return value 🫶

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

🔥 Exceptions 🔥

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

⭐ Complexity ⭐

Depends on underlying containers. Typically linear.

🚧 This section is incomplete Reason: revision required

🎀 Example 🎀

// Run this code

#include <flat_map>
#include <iostream>

int main()
{
    std::flat_map<int, std::string> c =
    {
        {1, "one"}, {2, "two"}, {3, "three"},
        {4, "four"}, {5, "five"}, {6, "six"}
    };

    // erase all odd numbers from c
    for (auto it = c.begin(); it != c.end();)
    {
        if (it->first % 2 != 0)
            it = c.erase(it);
        else
            ++it;
    }

    for (auto& p : c)
        std::cout << p.second << ' ';
    std::cout << '\n';
}

Output:

two four six

🦋 See also 🦋

• clear — clears the contents (public member function).

👑 Category 👑

• Todo with reason

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xoxo, your Unix bestie 💖 — source/version: http://cppreference.com, date: 2024.06.10, page: std::flat_map::erase(3). mwah 💋