Regex Question. Match pattern in a string

Question

basically in need that a whole string is a match if it has the following pattern:

DIGITS SPACE WORDS(min. 1 to a max of 3.) SPACE

So the following string will be a match:

30 boxes 30 boxes 30 boxes boxes boxes

But the following won't match:

30 boxes 30 boxes boxes boxes boxes 30 boxes

NOTE: the last character in a row is a space

I have the following regex up until now:

(\d+)(\s)(([a-zA-Z]+)(\s)){1,3}

By "strings" do you mean "letters" or "words" or something else? Also, I can't understand why the first example matches and the seconds one does not. Please clarify your question. — Bohemian
– Bohemian ♦, Commented Dec 30, 2018 at 21:30
The 1st one is satisfied because between each pair of integers there are a max. of 3 words i.e. boxes is written 3 times. In the 2nd instance, there is boxes written 4 times which should be incorrect as stated by the regex statement {1,3} — user41181
– user41181, Commented Dec 30, 2018 at 22:01

Wiktor Stribiżew · Accepted Answer · 2018-12-31 16:25:40Z

1

I suggest using

^(?:\d+(?:\s+[a-zA-Z]+){1,3}\s*)+$

See the regex demo

It matches

^ - start of string
(?:\d+(?:\s+[a-zA-Z]+){1,3}\s*)+ - one or more occurrences of
- \d+ - 1 or more digits
- (?:\s+[a-zA-Z]+){1,3} - one, two or three occurrences of
  - \s+ - 1+ whitespaces
  - [a-zA-Z]+ - 1+ ASCII letters
\s* - 0+ whitespaces
$ - end of string.

answered Dec 31, 2018 at 16:25

Wiktor Stribiżew

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2 Comments

JohnyL Over a year ago

Your pattern doesn't work for "30 boxes 30 boxes boxes boxes boxes 30 boxes " case.

Wiktor Stribiżew Over a year ago

@JohnyL It should fail, so it works. boxes boxes boxes boxes contains 4 words and the requirement is min. 1 to a max of 3..

JohnyL · Accepted Answer · 2018-12-31 19:08:15Z

1

var s = "30 boxes 30 boxes boxes boxes boxes 30 boxes ";
var pattern = @"(?i)^(\d+(\s+[a-z]+\s*)+){1,3}$";
WriteLine($"Is match: {Regex.IsMatch(s, pattern)}"); // => Is match: true

answered Dec 31, 2018 at 19:08

JohnyL

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