CODEWITHSUNDEEP
regex
Downhillski
Downhillski

Reputation: 2655

Test the beginning and the end of the input is not space

I want to select those who doesn't begin or end with space.

Test String:

  ad 
bui sfa
daf
a
fa  
    12

Attempted Regex (with no match ;(... ):

^[^\s]*.*[^\s]*$

Here is the link.

Upvotes: 2

Views: 2294

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626896

Your regex ^[^\s]*.*[^\s]*$ does not work because you applied * quantifier to the [^\s] negated character classes matching any symbol but whitespace, thus making this optional. Also, your input looks to be multiline, so in the online regex tester, you'd need to specify the /m multuline flag to see if the lines match your pattern. Also, the pattern requires at least two symbols to be present in the input string, but you also have a a line (containing 1 symbol) - and it wouldn't get matched.

You can use

^(?!\s|.*\s$).*$

See the regex demo. Note the use of the /m multiline flag (necessary if your input is multiline). This pattern allows any string that does not begin or end with a whitespace.

A more detailed explanation:

  • ^ - start of a line
  • (?!\s|.*\s$) - a negative lookahead that fails a match if the string starts (due to the first \s) or (|) ends (due to .*\s$) with whitespace
  • .*$ - actually matches a line up to the end.

Upvotes: 4

Lars Fischer
Lars Fischer

Reputation: 10149

Try the regex: ^\S+(.*\S+)?$.

  • \s is a character class, that contains whitespaces. \S is the negated class. It stands for non-whitespaces.
  • ^ matches at the beginning of a line.
  • ^\S+ matches one or more non-whitspaces at the beginning of a line
  • lets have a look at the second part: (.*\S+)? :
    • `.* means zero or more arbitrary chars
    • \S+ is again one or more non-whitspaces
    • (...)? the question marks makes the part inside the parentheses optional. This makes the line a match.
  • $ means "at the end of a line".

Upvotes: 3

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