c++11 - What is an effective POSIX define check for mmap support?

Question

I'm coming from a windows background so I'm a bit new here, but I'm trying to conditionally use mmap() but only if the platform supports it.

I know now it's a POSIX standard, and I'd like to check for it in my code. However, I'm confused as to the best way to do it.

https://pubs.opengroup.org/onlinepubs/9699919799/functions/mmap.html

Looking here it says this: CHANGE HISTORY First released in Issue 4, Version 2.

I don't know how to translate to an #if check.

I want to check the POSIX version to make sure its defined and at minimum the version in which mmap is supported.

Google doesn't seem to be much help here.

#if ?????
// code to use mmap()
#endif

That's what I want. Just the ???? part

Thanks in advance.

Answer 1

等待大神答复