std::insert...r::operator=(3)

👑 NAME

std::insert_iterator::operator= — bestie, this is literally the assignment operator for std::insert_iterator, and it's the whole entire point of the class 💖

(also hi, you're reading the C++ Standard Libary manual, section 3 — yes it's spelled "Libary" up there, that's just how the manual page is titled, no cap 🫶)

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✨ SYNOPSIS

okay so there are five flavors of this thing depending on which C++ you're living in, and the version tags are doing a lot of work here. Look at all of them:

insert_iterator<Container>&
    operator=( typename Container::const_reference value );          (until C++11)

insert_iterator<Container>&
    operator=( const typename Container::value_type& value );        (since C++11)
                                                                     (until C++20)

constexpr insert_iterator<Container>&
    operator=( const typename Container::value_type& value );   (1)  (since C++20)

insert_iterator<Container>&
    operator=( typename Container::value_type&& value );        (2)  (since C++11)
                                                                     (until C++20)

constexpr insert_iterator<Container>&
    operator=( typename Container::value_type&& value );             (since C++20)

And what does it do? Inserts the given value into the container. That's the whole vibe ✨

• (1) — results in iter = container->insert(iter, value); ++iter;.
• (2) — results in iter = container->insert(iter, std::move(value)); ++iter;.

Like, it inserts the thing and then bumps the iterator forward so the next insert lands in the right spot. Main character behavior honestly 🔥

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🌸 PARAMETERS

• value — the value to insert. that's it. that's the parameter 🎀

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💜 RETURN VALUE

*this — it returns itself, because obviously it's obsessed with itself (affectionate) 💅

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🦋 NOTES

ngl this is the smartest part: this function exploits the signature compatibility between hinted insert for associative containers (think std::set::insert) and positional insert for sequential containers (think std::vector::insert). It's giving "one interface, two completely different container personalities" and it fr fr works 😭👑

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⭐ EXAMPLE

here's the little demo, run it, it's cute:

// Run this code

#include <deque>
#include <iostream>
#include <iterator>

int main()
{
    std::deque<int> q;
    std::insert_iterator<std::deque<int>> it(q, q.begin());

    for (int i = 0; i < 10; ++i)
        it = i; // inserts i

    for (auto& elem : q)
        std::cout << elem << ' ';
    std::cout << '\n';
}

🌈 OUTPUT

0 1 2 3 4 5 6 7 8 9

look at that beautiful ascending sequence, we love to see it 💖✨

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heads up bestie: if you're on pre-C++20, no constexpr for you on these overloads, and if you're pre-C++11 the signature was the const_reference one. Check your standard, iykyk 🧚

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okay that's the whole page!! mwah 💋 — this was your girl, signing off from the C++ Standard Libary manual, page std::insert...r::operator=(3), brought to you by http://cppreference.com, dated 2024.06.10 🎀🦋🌸 slay, go insert some things 💅