std::deque::emplace_front(3)

💖 std::deque::emplace_front 💖

Okay bestie, welcome to the std::deque::emplace_front page from the C++ Standard Libary (yes, that’s the manual name in the header, spelling and all 💅). This is the C++ Standard Library glow-up for putting a brand-new element at the very front of a std::deque.

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🌸 NAME 🌸

std::deque::emplace_front — std::deque::emplace_front

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📜 Synopsis

Here’s the signature tea, exactly as written:

template< class... Args >                   (since C++11)
void emplace_front( Args&&... args );       (until C++17)
template< class... Args >                   (since C++17)
reference emplace_front( Args&&... args );

So what does it do? It inserts a new element to the beginning of the container. The element is constructed through std::allocator_traits::construct, which typically uses placement-new to construct the element in-place at the location provided by the container. The arguments args... are forwarded to the constructor as std::forward<Args>(args)....

And the iterator tea? 🚨 All iterators (including the end() iterator) are invalidated. No references are invalidated. So your references stay safe, but your iterators are absolutely not coming to the function.

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🧸 Parameters

• args — arguments to forward to the constructor of the element

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🧚 Type requirements

• T (the container's element type) must meet the requirements of EmplaceConstructible.

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🎁 Return value

• (none) — until C++17
• A reference to the inserted element. — since C++17

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⚡ Complexity

Constant. Short and sweet, no cap.

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💀 Exceptions

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee). So if it goes wrong, it’s giving “nothing happened here” energy. 💅

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👀 See also

• push_front — inserts an element to the beginning (public member function)

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Source: http://cppreference.com · version/date: 2024.06.10 · page: std::deque::emplace_front(3) — bye bestie, go emplace responsibly 💅✨