What C standard should I be using for portability?

Question

I was just wondering which C standard I should be using to code. Since GCC 15 automatically sets the default to C23, I was wondering if there's any differences between C17 or C99 and which one I should be using for the most portability across Linux and BSD

Answer 1

According to information from websites:
You should use C99. It has been supported by GCC, Clang and other BSD compilers for a long time, more than a decade.
Many of the older systems which don't support C11/17 mostly support C99.
Also it has features you'd commonly use in C like:
single line comments, Boolean data type, long long and inline functions.
So you should choose C99

Answer 2

Thank you for the response