CODEWITHSUNDEEP
.netregex
Gabriel I.
Gabriel I.

Reputation: 123

regex - Start to match after certain pattern

I'm having trouble when trying to find stuff with regex.

I have the following regex

([{\-\+~a-zA-Z0-9]+){3,}

And it works as it should, however, I need to capture all possible matches AFTER a certain character, which in this case is }.

faz.}a..sd..3·$....................foo....e..P...0...................bar

foo and bar must match, but faz shouldn't. Note that I can't use .+(?=}) because it captures everything after the } into a single match. I searched in the internet and every answer suggested this pattern.

Thanks in advance.

Upvotes: 1

Views: 397

Answers (2)

user557597
user557597

Reputation:

Get it all at once with a simplified and quicker CaptureCollection

(?s)}(?:.*?([{\-+~a-zA-Z0-9]{3,}))+

Read version 

 (?s)
 }
 (?:
      .*? 
      ( [{\-+~a-zA-Z0-9]{3,} )      # (1)
 )+

C# 

string inp = @"faz.}a..sd..3·$....................foo....e..P...0...................bar";
Regex Rx1 = new Regex( @"(?s)}(?:.*?([{\-+~a-zA-Z0-9]{3,}))+" );
Match M1 = Rx1.Match( inp );
if ( M1.Success )
{
    CaptureCollection cc = M1.Groups[1].Captures;
    for (int i = 0; i < cc.Count; i++)
        Console.WriteLine("{0}", cc[i].Value);
}

Output 

foo  
bar  
Press any key to continue . . .

Upvotes: 0

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626748

In .NET, you may use a positive variable length lookbehind to match the pattern occurrences only after a certain char/substring/pattern:

(?<=}.*)[-{+~a-zA-Z0-9]{3,}
^^^^^^^^

See the regex demo

Details

  • (?<=}.*) - a } (and any 0+ chars other than a newline) should be present before the subsequent cosuming pattern part
  • [-{+~a-zA-Z0-9]{3,} - 3 or more occurrences of letters, digits and some punctuation/symbol chars listed in the character class.

You might also check an opposite approach: match the words you need if they are not followed with }:

[-{+~a-zA-Z0-9]{3,}(?![^}]*})

See this regex demo.

Here, (?![^}]*}) is a negative lookahead that fails the match if there is a } after any 0+ chars other than } immediately to the right of the "word" matched with the [-{+~a-zA-Z0-9]{3,} pattern.

Upvotes: 1

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