PHP preg_match needed to ensure only ONE space character is allowed between words

Question

basically I need a preg_match that ensures that only one space character is allowed between each word (IF there is more than one word).

My existing rule is:

Answer 1

/^[\S]+\s?[^\s]?/i

Will search for any word with one space after it and not a space after that one space

/\s?\S+\s/

Will search for any character with whitespace on either side or only on the end.