std::front_inserter(3)

std::front_inserter(3)

Okay so this page lives under the C++ Standard Libary manual name — yes, that's the spelling in the header, bestie, and we're keeping it 💖. It's the std::front_inserter page, and it's giving tiny-helper-that-slays energy. 🎀

💖 NAME 💖

std::front_inserter — literally std::front_inserter. That's the name. No cap, it's giving "the function is the name" main character energy. ✨

🌸 Synopsis 🌸

Defined in header <iterator>
template< class Container >
constexpr std::front_insert_iterator<Container> front_inserter( Container& c );

It's constexpr since C++20, bestie — the manpage note is (constexpr since C++20), and yes, that's iconic. 💅

Okay so front_inserter is a convenience function template 🫶. It constructs a std::front_insert_iterator for the container c, and the type is deduced from the type of the argument. It's giving helper-function main character energy, fr fr. ✨

🎀 Parameters 🎀

• c — a container that supports a push_front operation. That's the vibe check, bestie: if it can't push_front, it's not passing. 💅

🦋 Return value 🦋

Returns a std::front_insert_iterator — and you can use it to add elements to the beginning of the container c. Slay. 💖

✨ Possible implementation ✨

Here's the possible implementation, and yes it's literally this simple:

template<class Container>
std::front_insert_iterator<Container> front_inserter( Container& c )
{
    return std::front_insert_iterator<Container>(c);
}

🌸 Example 🌸

Run this code, bestie:

// Run this code

#include <algorithm>
#include <deque>
#include <iostream>
#include <iterator>
#include <vector>

int main()
{
    std::vector<int> v{1, 2, 3, 4, 5};
    std::deque<int> d;
    std::copy(v.begin(), v.end(), std::front_inserter(d));
    for (int n : d)
        std::cout << n << ' ';
    std::cout << '\n';
}

🍓 Output 🍓

5 4 3 2 1 — the example ate and left no crumbs. 💅

🌈 See also 🌈

• front_insert_iterator — iterator adaptor for insertion at the front of a container. (class template)
• back_inserter — creates a std::back_insert_iterator of type inferred from the argument. (function template)
• inserter — creates a std::insert_iterator of type inferred from the argument. (function template)

mwah 💋 — this page's source is http://cppreference.com and its version/date is 2024.06.10. Bye bestie! 🫶