c++ - What's the best "type renaming" method? -

if wanted rename std::string type simpler , more naturally looking string, of these 2 methods should use (based on performance , standard)

should rename preprocessed directive

#define string std::string 

or type definition

typedef std::string string; 

what's performant method? more familiar , recognized community?

just

using std::string; 

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if want different name, e.g.

using string = std::string; 

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avoid macros, don't respect scopes , evil™.

for example, proposed macro

#define string std::string 

… yields formal undefined behavior if include standard library header, because defines name used standard library.

c++11 §17.6.4.2.2/1 [macro.names]:

” translation unit includes standard library header shall not #define or #undef names declared in standard library header.