std::basic_..._view::copy(3)

💖 NAME 💖

std::basic_string_view::copy — std::basic_string_view::copy (yes bestie, the name is the name, she's self-titled and iconic 💅).

hey bestie 💖 welcome to the std::basic_..._view::copy(3) page from the C++ Standard Libary. We're gonna get you all the way together on this member function, fr fr.

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✨ Synopsis ✨

size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const;

• (since C++17) — this is the C++17-and-later era, periodt.
• (constexpr since C++20) — and it got the constexpr glow-up in C++20 ✨.

Copies the substring [pos, pos + rcount) to the character array pointed to by dest, where rcount is the smaller of count and size() - pos.

Equivalent to Traits::copy(dest, data() + pos, rcount).

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🌸 Parameters 🌸

• dest — pointer to the destination character string.
• count — requested substring length.
• pos — position of the first character.

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🎀 Return value 🎀

Number of characters copied.

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🚨 Exceptions 🚨

std::out_of_range if pos > size().

bestie, if pos is bigger than size(), the vibe check fails and you get std::out_of_range 😭.

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⚡ Complexity ⚡

Linear in rcount.

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🍓 Example 🍓

       // Run this code

        #include <array>
        #include <cstddef>
        #include <iostream>
        #include <stdexcept>
        #include <string_view>

        int main()
        {
            constexpr std::basic_string_view<char> source{"ABCDEF"};
            std::array<char, 8> dest;
            std::size_t count{}, pos{};

            dest.fill('\0');
            source.copy(dest.data(), count = 4); // pos = 0
            std::cout << dest.data() << '\n'; // ABCD

            dest.fill('\0');
            source.copy(dest.data(), count = 4, pos = 1);
            std::cout << dest.data() << '\n'; // BCDE

            dest.fill('\0');
            source.copy(dest.data(), count = 42, pos = 2); // ok, count -> 4
            std::cout << dest.data() << '\n'; // CDEF

            try
            {
                source.copy(dest.data(), count = 1, pos = 666); // throws: pos
       > size()
            }
            catch (std::out_of_range const& ex)
            {
                std::cout << ex.what() << '\n';
            }
        }

💬 Output 💬

        ABCD
        BCDE
        CDEF
        basic_string_view::copy: __pos (which is 666) > __size (which is 6)

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🌈 See also 🌈

• substr — returns a substring (public member function).
• copy — copies characters (public member function of std::basic_string<CharT,Traits,Allocator>).
• copy — copies a range of elements to a new location.
• copy_if — (function template) (C++11).
• memcpy — copies one buffer to another (function).

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signed, sealed, delivered by std::basic_..._view::copy(3) from http://cppreference.com, dated 2024.06.10 💌✨