std::deque::clear(3)

💖 NAME 💖

std::deque::clear — std::deque::clear

okay so bestie, welcome to std::deque::clear(3) from the C++ Standard Libary manual. Yes, the NAME line is literally the same thing twice — it’s giving minimal, it’s giving icon behavior 💅.

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✨ Synopsis ✨

void clear();  (noexcept since C++11)

This is the whole signature, no cap. It’s marked noexcept since C++11 exactly like that ✨.

What it does: Erases all elements from the container. After this call, size() returns zero. Periodt.

⚠️ Invalidates any references, pointers, and iterators referring to contained elements. Any past-the-end iterators are also invalidated. So yeah, don’t be holding onto old iterators like they’re still valid — they are not, bestie 😭.

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🫶 Parameters 🫶

• (none) — no arguments, no stress, no little parameter besties to feed.

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🎀 Return value 🎀

• (none) — it returns literally nothing. It just does the clear and dips.

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🌸 Complexity 🌸

Linear in the size of the container, i.e., the number of elements. So the bigger the deque, the more work it’s doing — fr fr.

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🦋 Example 🦋

The page gives the cue // Run this code, and then this exact code drops:

#include <iostream>
#include <string_view>
#include <deque>

void print_info(std::string_view rem, const std::deque<int>& v)
{
    std::cout << rem << "{ ";
    for (const auto& value : v)
        std::cout << value << ' ';
    std::cout << "}\n";
    std::cout << "Size=" << v.size() << '\n';
}

int main()
{
    std::deque<int> container{1, 2, 3};
    print_info("Before clear: ", container);
    container.clear();
    print_info("After clear: ", container);
}

🌟 Output 🌟

Before clear: { 1 2 3 }
Size=3
After clear: { }
Size=0

ate. no crumbs. the deque really said “empty era” 🫶✨

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💅 Defect reports 💅

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

• DR: LWG 2231
• Applied to: C++11
• Behavior as published: complexity guarantee was mistakenly omitted in C++11
• Correct behavior: complexity reaffirmed as linear

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👑 See also 👑

• erase — erases elements (public member function)

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source/date sign-off: http://cppreference.com · 2024.06.10 💖✨