std::list::push_front(3)

💅 std::list::push_front — C++ Standard Library

Okay bestie, gather round, because today we're talking about std::list::push_front, straight out of the C++ Standard Library, and honestly? It's giving "small but mighty." ✨

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🌸 NAME

std::list::push_front — yes that's literally the whole name, it does what it says on the tin, and it is std::list::push_front. Iconic of it to be so upfront about it 💖

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🎀 Synopsis

void push_front( const T& value ); (1)
void push_front( T&& value );      (2) (since C++11)

So what's the vibe? It prepends the given element value to the beginning of the container. That's it. That's the whole job, and it does it flawlessly 👑

And the best part — say it with me — no iterators or references are invalidated. Your iterators stay valid, your references stay valid, nobody gets ghosted. Periodt. 💅

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🦋 Parameters

• value — the value of the element you're prepending. That's your lil star of the show ⭐

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🌈 Return value

(none) — it returns nothing, it just does the thing. Main character energy: no notes, no receipts, just results 🫶

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⭐ Complexity

Constant. O(1) bestie, we love a constant-time queen 👑

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🔥 Exceptions

If an exception is thrown for any reason, these functions have no effect — that's the strong exception safety guarantee, and it means it's all-or-nothing. Either the element gets prepended, or nothing happened at all. No messy half-states here, no cap 🧚

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💜 Example

// Run this code

#include <list>
#include <iomanip>
#include <iostream>
#include <string>

int main()
{
    std::list<std::string> letters;

    letters.push_front("abc");
    std::string s{"def"};
    letters.push_front(std::move(s));

    std::cout << "std::list letters holds: ";
    for (auto&& e : letters)
        std::cout << std::quoted(e) << ' ';

    std::cout << "\nMoved-from string s holds: " << std::quoted(s) << '\n';
}

Fr fr go run this, it's a cute lil demo 🍓

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🔮 Possible output

std::list letters holds: "def" "abc"
Moved-from string s holds: ""

Notice how "def" ended up in front of "abc"? That's the whole push-front lifestyle 💅 And the moved-from string s is empty now — that's just what happens when you std::move something, iykyk 🌸

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👑 See also

• emplace_front — constructs an element in-place at the beginning (C++11) (public member function)
• push_back — adds an element to the end (public member function)
• pop_front — removes the first element (public member function)
• front_inserter — creates a std::front_insert_iterator of type inferred from the argument (function template)

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And that's the whole page, bestie! 🎀 This one's from http://cppreference.com, dated 2024.06.10, and it's the std::list::push_front(3) page — go forth and prepend responsibly 💖✨