std::wcscpy

#include <iostream>
#include <cwchar>
#include <memory>
#include <clocale>
 
int main()
{
    const wchar_t* src = L"犬 means dog";
//  src[0] = L'狗'; // 不能修改字符串字面量
    auto dst = std::make_unique<wchar_t[]>(std::wcslen(src)+1); // 为空宽字符 +1
    std::wcscpy(dst.get(), src);
    dst[0] = L'ç‹—';
    std::setlocale(LC_ALL, "en_US.utf8");
    std::wcout.imbue(std::locale(""));
    std::wcout << src << '\n' << dst.get() << '\n';
}