c++ - C++ 对字 rune 字的顺序有什么保证？

Question

C++ 对字 rune 字的顺序有什么保证？ 基本源字符集中的字符有明确的顺序吗？ (例如 'a' < 'z' 保证是真的吗？'A' < 'z' 怎么样？)

Answer 1

该标准仅保证十进制数字 0 到 9 的顺序，来自草案 C++11 标准部分 2.3 [lex.charset]:

In both the source and execution basic character sets, the value of each character after 0 in the above list of decimal digits shall be one greater than the value of the previous.

否则说(强调我的):

The basic execution character set and the basic execution wide-character set shall each contain all the members of the basic source character set, plus control characters representing alert, backspace, and carriage return, plus a null character (respectively, null wide character), whose representation has all zero bits. For each basic execution character set, the values of the members shall be non-negative and distinct from one another.

请注意，EBCDIC具有非连续字符集。