c++ - 是否根据最新的 C++ 标准保留以下划线开头的标识符？

Question

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Answer 1

是的，当下划线后跟另一个下划线或大写字母(即预处理器 #defines 或宏)时，或者如果标识符位于全局命名空间中(§17.6.4.3.2):

Certain sets of names and function signatures are always reserved to the implementation:

— Each name that contains a double underscore _ _ or begins with an underscore followed by an uppercase letter (2.12) is reserved to the implementation for any use.

— Each name that begins with an underscore is reserved to the implementation for use as a name in the global namespace.

注意，第一点的意思是，如果两个下划线出现在标识符中任何地方，即使是在中间或者末尾，这个名字也是保留的。另外，我要添加(§17.6.4.3.5，强调我的):

Literal suffix identifiers that do not start with an underscore are reserved for future standardization.