【字符集八】char8

参考：

• char :
  c++中的关键字,占用1个字节。

• wchar_t
  https://www.educba.com/c-plus-plus-wchar_t/

• char16_t、char32_t
  https://en.cppreference.com/w/c/string/multibyte/char16_t

• char8_t：c++20标准中新增加的关键字。
  https://open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0482r6.html

#include 
using namespace std;
int main()
{
    //char* loc = setlocale(LC_ALL,".65001");

    char ch[] = "我";
    char8_t ch8[] = u8"我";
    wchar_t wch[] = L"我";
    char16_t ch16[] = u"我";
    char32_t ch32[] = U"我";

    cout << &ch< 
输出：
 
 
 
00B7F83C
 00B7F830
 00B7F824
 00B7F818
 00B7F808
 ch:0xffffffe60xffffff880xffffff910
 ch8:0xffffffe60x880x910
 wch:0x6211
 ch16:0x6211
 ch32:0x6211
 
 
 
utf-8的中文是一个汉字占三个字节长度吗？
 
四、分析 
char和char8_t中存的数字为：e6 88 91。代表汉字我的字符编码，三个字节，计算方式参考字符集vs字符编码。安装文章中的计算方式，换算后也是等于62 11.
wchar_t、char16_t、char_32t中存的数字为：62 11。其中6211为Unicode的汉字”我"的字符编码；参见汉字的宽字符码和多字节码分别是多少
 
五、c++20标准：char8_t不可以输出 
 
 
Recap
 char8_t can not hold a full range of utf-8 glyphs. utf-8 glyphs can be up to 4 bytes. char8_t holds up to 1 byte.
 char8_t stream out is expressly forbidden in C++20
 for utf-8 compatibility while in VStudio use char and the /utf-8 switch
 in case you really want C++20 way of transforming to/from char8_t, you need to use … AFAIK not yet fully implemented in any of the 3, as required by the standard
 
 
参见：C++20 char8_t, the Boson