std::deque::operator[](3)

okay so bestie, welcome to the <pink>std::deque::operator[]</pink> page in section (3) of the C++ Standard Libary manual. Yes, the header spells it “Libary” — we're keeping that exactly as-is, and honestly? iconic. 💅

🌸 NAME 🌸

std::deque::operator[] - std::deque::operator[]

That's the name, bestie. It's giving “the bracket-bracket operator of the deque.” 🎀

📜 Synopsis 📜

reference operator[]( size_type pos );             (1)
const_reference operator[]( size_type pos ) const; (2)

Okay so these signatures return a reference to the element at specified location pos. And no bounds checking is performed. Not a little, not a tiny bit — none. 🙈

🎯 Parameters 🎯

• pos — position of the element to return. That's the whole parameter. Slay. ✨

🫶 Return value 🫶

Reference to the requested element. That's it, that's the return value. 💖

⚡ Complexity ⚡

Constant. That is the entire complexity section, and it ate. ⭐

📝 Notes 📝

• Unlike std::map::operator[], this operator never inserts a new element into the container. Not ever. 🙅‍♀️
• Accessing a nonexistent element through this operator is undefined behavior. Like, do not do it, bestie. That's the warning. 💀

🍓 Example 🍓

The following code uses operator[] to read from and write to a std::deque<int>:

// Run this code

#include <deque>
#include <iostream>

int main()
{
    std::deque<int> numbers{2, 4, 6, 8};

    std::cout << "Second element: " << numbers[1] << '\n';

    numbers[0] = 5;

    std::cout << "All numbers:";
    for (auto i : numbers)
        std::cout << ' ' << i;
    std::cout << '\n';
}

✨ Output ✨

Second element: 4
All numbers: 5 4 6 8

👑 See also 👑

• at — access specified element with bounds checking (public member function). Yeah, at is the one doing the bounds checking. 💅

mwah 💋 — source/version and date: http://cppreference.com, 2024.06.10. Bye bestie, go index responsibly! 🌈🦋