std::vector::front(3)

std::vector::front(3) — C++ Standard Libary 💅

okay so bestie, welcome to the std::vector::front page from the C++ Standard Libary (yes, the header spells it “Libary” — we’re keeping the typo, it’s iconic). This one is short, sweet, and lowkey essential: it hands you the first element of your vector. Let’s get into it. 🦋✨

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NAME 🎀

std::vector::front - std::vector::front

That’s the NAME section, and it said the same thing twice. We respect it. 💅

Synopsis 🦋

reference front();             (1) (constexpr since C++20)
const_reference front() const; (2) (constexpr since C++20)

Returns a reference to the first element in the container.

⚠️ Calling front on an empty container causes undefined behavior. Like, actual undefined behavior. Not a cute look. Check that container first, bestie. 😭💀

Parameters 🎀

(none)

Literally no parameters. Zero. Nada. The parameter list is empty and it’s serving minimalist main character energy. 💅

Return value 💖

Reference to the first element.

That’s it. That’s the return value. First element, reference, slay. ✨

Complexity ⭐

Constant.

Constant. No cap. ⭐

Notes 🌸

For a container c, the expression c.front() is equivalent to *c.begin().

iykyk. 🫶

Example 🔥

The following code uses front to display the first element of a std::vector<char>:

(The original page also had // Run this code — that’s the official example vibe. Here’s the code:)

        #include <vector>
        #include <iostream>

        int main()
        {
            std::vector<char> letters{'a', 'b', 'c', 'd', 'e', 'f'};

            if (!letters.empty())
                std::cout << "The first character is '" << letters.front() <<
       "'.\n";
        }

Output:

The first character is 'a'.

See also 👀

• back — access the last element (public member function)

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okay that’s the whole page, bestie. It came from http://cppreference.com, version/date 2024.06.10, and it’s the std::vector::front(3) page. Go get that first element — but check empty() first, fr fr. 💖✨🎀