Everything that this parameter does automatically sets the preprocessor symbol. Either /D UNICODE , or /D _MBCS or nothing.
This is the setting that you decide very early and never change. With a bias towards Unicode, it makes no sense to write C ++ code and deliberately slow it down using the Ansi adapter functions. Visual Studio basically has this option, because there are so many codebases that started life 20 years ago, when the character set still seemed like a practical idea, and Win9x is still popular. Those days are over.
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