POSIX in g++

[Ian Lance Taylor]

"Peng Yu" <pengyu.ut@gmail.com> writes:

I should have said in reply to your last message: this is the wrong
mailing list for this question.  Please take any followups to
gcc-help@gcc.gnu.org.  Thanks.

> Isn't ANSI C++ a subset of POSIX C++. Why do I need to specify
> _POSIX_SOURCE,  _POSIX_C_SOURCE and -ansi?

ANSI C is a subset of POSIX C (as far as I know C++ is not a part of
POSIX).  Using -ansi restricts you to ANSI C.  Adding the POSIX
defines tells the library to declare POSIX functions in the POSIX
header files.


> Would you please let me know what is the difference between the option
> -ansi and -std?

Please read the fine manual.

Ian