std::wmemcpy(3)

💅 NAME 💅

Okay so this is the manual page for std::wmemcpy(3) from the C++ Standard Libary (yes, that's the typo in the header, and we're leaving it 💀). The function is std::wmemcpy — NAME literally says std::wmemcpy - std::wmemcpy, which is giving "I have one job and it's copying wide characters" energy. Periodt.

🌸 Synopsis 🌸

Defined in header <cwchar>:

Defined in header <cwchar>
wchar_t* wmemcpy( wchar_t* dest, const wchar_t* src, std::size_t count );

It copies exactly count successive wide characters from the wide character array pointed to by src to the wide character array pointed to by dest. If the objects overlap, the behavior is undefined — like, not "maybe weird", actually undefined, bestie 😭. If count is zero, the function does nothing. Zero. Nada. It simply vibes.

🎀 Parameters 🎀

• dest — pointer to the wide character array to copy to 🫶
• src — pointer to the wide character array to copy from ✨
• count — number of wide characters to copy 🔢

💖 Return value 💖

dest — that's it. That's the whole return value. Iconic, honestly.

🦋 Notes 🦋

This function's analog for byte strings is std::strncpy, not std::strcpy — not me stressing this difference, but here we are 💅.

This function is not locale-sensitive and pays no attention to the values of the wchar_t objects it copies: nulls as well as invalid characters are copied too. It's not judging, it's just copying, no cap.

✨ Example ✨

// Run this code

#include <clocale>
#include <cwchar>
#include <iostream>
#include <iterator>
#include <locale>

int main(void)
{
    const wchar_t from1[] = L"नमसत";
    const wchar_t from2[] = L"Բարև";
    const std::size_t sz1 = std::size(from1);
    const std::size_t sz2 = std::size(from2);
    wchar_t to[sz1 + sz2];

    std::wmemcpy(to, from1, sz1); // copy from1, along with its null terminator
    std::wmemcpy(to + sz1, from2, sz2); // append from2, along with its null terminator

    std::setlocale(LC_ALL, "en_US.utf8");
    std::wcout.imbue(std::locale("en_US.utf8"));
    std::wcout << L"Wide array contains: ";
    for (std::size_t n = 0; n < std::size(to); ++n)
        if (to[n])
            std::wcout << to[n];
        else
            std::wcout << L"\\0";
    std::wcout << L'\n';
}

🌈 Possible output 🌈

Wide array contains: नमसत\0Բարև\0

👑 See also 👑

• strncpy — copies a certain amount of characters from one string to another (function) 🎀
• wmemmove — copies a certain amount of wide characters between two, possibly overlapping, arrays (function) 🦋
• C documentation for wmemcpy 📚

Signed with sparkles and zero overlap, bestie 💌 — source: http://cppreference.com, version/date: 2024.06.10, manual page: std::wmemcpy(3). Mwah! 💋