Don't use atoi. Use std::from_chars.
This makes sense for integers but beware floating point from_chars - libc++ still doesn't implement it and libstdc++ implements it by wrapping locale-dependent libc functions which involves temporarily changing the thread locale and possibly memory allocation to make the passed string 0-terminated. IMO libstdc++'s checkbox "solution" is worse than not implementing it at all - user's are better off using Lemire's API-compatible fast_float implementation [0].
Of course it's possible that the author wanted to support compilers released before 2018 when that code was written in which case not even integer from_chars would be available.