Regex matching all but not empty

Question

A line has to be validated through regex,

line can contain any characters, spaces, digits, floats.
line should not be blank

I tried this:

[A-Za-z0-9~`!#$%^&*()_+-]+ //thinking of all the characters

Any alternative solution will be helpful

So you're saying that absolutely anything is allowed, as long as the line isn't empty? Why do you even want to use a regex for this, as opposed to the `length` function that I'm sure your language has? — ruakh, Jul 23 '12 at 19:37
do you need regex for this? why not just trim the line and check if it is not an empty string? — jay c., Jul 23 '12 at 19:38
For `2. line should not be blank` -- should a line containing only whitespace be counted as "blank" or not? It makes a difference to the regex or to non-regex methods. — Stephen P, Jul 23 '12 at 20:23
I believe this answer will help you. Good luck! http://stackoverflow.com/questions/3085539/regular-expression-for-anything-but-an-empty-string-in-c-sharp — Slavik Meltser, Jul 14 '13 at 11:23

Timo Huovinen · Answer 1 · 2015-06-22T05:28:10.303

32

Try this to match a line that contains more than just whitespace

/.*\S.*/

This means

/ = delimiter
.* = zero or more of anything but newline
\S = anything except a whitespace (newline, tab, space)

so you get
match anything but newline + something not whitespace + anything but newline

if whitespace only line counts as not whitespace, then replace the rule with /.+/, which will match 1 or more of anything.

edited Jun 22 '15 at 05:28

answered Mar 27 '14 at 10:32

Timo Huovinen

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Still works in 2023! I used this variation for search and replace in **Notepad++**: Find: `(.*) \S`, REPLACE WITH: `- \1`. This adds a dash and space in front of every non blank line essentially converting the items to a bullet list for **markdown** like in SO – Eric Hepperle - CodeSlayer2010 Aug 03 '23 at 12:57

score 18 · Answer 2 · edited Aug 09 '18 at 10:43

18

try:

.+

The . matches any character, and the plus requires least one.

edited Aug 09 '18 at 10:43

Robert

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answered Jul 23 '12 at 19:37

B.K.

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-1, sorry. In most regex engines, `[.]` will only match an actual period. You mean `.`. – ruakh Jul 23 '12 at 19:38

Zulu · Answer 3 · 2015-03-24T15:17:27.070

7

Try : [^()]

In python with re.match() :

  >>> re.match( r"[^()]", '' )
  >>> re.match( r"[^()]", ' ' )
  <_sre.SRE_Match object at 0x100486168>

edited Mar 24 '15 at 15:17

answered Jul 23 '12 at 20:12

Zulu

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score 3 · Answer 4 · answered Jul 23 '12 at 19:39

3

You could just check if the line matches ^$ if it does then it's blank and you can use that as a failure, otherwise it will pass.

answered Jul 23 '12 at 19:39

hkothari

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score 3 · Answer 5 · answered Aug 10 '16 at 13:11

Try this:

^.+$

I used this in python BeautifulSoup when trying to find tags which do not have an attribute that is empty. It worked well. Example is below:

# get first 'a' tag in the html content where 'href' attribute is not empty
parsed_content.find("a", {"href":re.compile("^.+$")})

score 1 · Answer 6 · edited Mar 30 '19 at 05:56

1

try

^[A-Za-z0-9,-_.\s]+$

this string will return true for alphabets, numbers and ,-_. but will not accept an empty string.

+ -> Quantifier, Matches between 1 and unlimited.

* -> Quantifier, Matches between 0 and unlimited.

edited Mar 30 '19 at 05:56

xskxzr

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answered Mar 30 '19 at 05:37

Rishabh Shukla

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HannaY · Answer 7 · 2015-11-05T10:22:31.177

0

This one will match everything but NOT BLANK string:

^(\s|\S)*(\S)+(\s|\S)*$

Blank string is those containing empty characters only (tabs, spaces etc.).

edited Nov 05 '15 at 10:22

answered Nov 04 '15 at 17:25

HannaY

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score 0 · Answer 8 · answered Feb 06 '18 at 16:52

0

This one will match every line with at least 1 character:

(.*?(\n))

answered Feb 06 '18 at 16:52

roelvdboom

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score 0 · Answer 9 · answered Mar 04 '19 at 17:12

0

^\S+[^ ]$

^ - beginning of line

\S - any non-whitespace character

+ - one or more occurence

[^ ] - character not in the set (in this case only space), there is a space between ^ and ] this will match dsadasd^adsadas

$ - end of line

answered Mar 04 '19 at 17:12

xrayder

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Why is `[^ ]` needed? What does it match which `\S` does not? – Gili Sep 06 '19 at 03:24

score 0 · Answer 10 · answered Oct 08 '20 at 16:37

.* - matches between zero and unlimited times any character (except for line terminators)

\S - matches any non-whitespace character

Answer: .*[\S].*

'aaaaa' match

'aaaaa ' match

' aaaaa' match

' aaaaa ' match

'aaaaa aaaaa aaaaa' match

' aaaaa aaaaa aaaaa' match

'aaaaa aaaaa aaaaa ' match

' aaaaa aaaaa aaaaa ' match

' ' does not match

You can test this regular expression at: https://regex101.com

Regex matching all but not empty

10 Answers10