I've tried this

(?!\sa-zA-Z){4,}\s{1,}

• I want 4 or more characters and minimum 1 space anywhere in string, but doesn't work
• The space can be anywhere position without from start. I've try this, but that not work Regex: Allow minimum alphanumeric, dot and - characters. Asterisk allowed anywhere?

EDIT: I would like this result : aa aa..., aaa a..., a aaa..., aaaa ...

CodePudding user response：

You can use

\b[a-zA-Z](?=[a-zA-Z ]{3})[a-zA-Z]*  [a-zA-Z]*

Explanation

• \b A word boundary to prevent a partial word match
• [a-zA-Z] Match a single char a-zA-Z
• (?=[a-zA-Z ]{3}) Positive lookahead, assert 3 of the listed chars in the character class to the right of the current position
• [a-zA-Z]* [a-zA-Z]* Match optional chars a-zA-Z, then match 1 spaces space and again optional chars a-zA-Z

See a regex demo.