Then the programmer has made a mistake, because the behavior is the same as `strtod` in C locale, i.e. it stops parsing at the first comma. You should think of

Then the programmer has made a mistake, because the behavior is the same as `strtod` in C locale, i.e. it stops parsing at the first comma. You should think of `from_chars` as a function that accepts the outputs of `to_chars`, not as a general text understander.