How to capture multiple repeated groups

Question

I need to capture multiple groups of the same pattern  Suppose  I have a following string   HELLO THERE WORLD   And I ve written a following pattern          A-Z           What I want it to do is  capture every single word  so that Group 1 is    HELLO   Group 2 is  THERE  and Group 3 is  WORLD  What my regex is actually capturing only the last one  which is  WORLD    I m testing my regular expression here and I want to use it with Swift  maybe there s a way in Swift to get intermediate results somehow  so that I can use them    UPDATE  I don t want to use split  I just need to now how to capture all the groups that have matched the pattern  not only the last one

User · Answer

You actually have one capture group that will match multiple times. Not multiple capture groups.

javascript (js) solution:

let string = "HI,THERE,TOM";
let myRegexp = /([A-Z]+),?/g;       //modify as you like
let match = myRegexp.exec(string);  //js function, output described below
while(match!=null){                 //loops through matches
    console.log(match[1]);          //do whatever you want with each match
    match = myRegexp.exec(bob);     //find next match
}

Output:

HI
THERE
TOM

Syntax:

// matched text: match[0]
// match start: match.index
// capturing group n: match[n]

As you can see, this will work for any number of matches.

User · Answer

I know that my answer came late but it happens to me today and I solved it with the following approach       A-Z        A-Z       So the first group    A-Z       will match all the repeated patterns except the final one   A-Z    that will match the final one  and this will be dynamic no matter how many repeated groups in the string

User · Answer

Sorry  not Swift  just a proof of concept in the closest language at hand     JavaScript POC  Output     Matches     quot GOODBYE quot   quot CRUEL quot   quot WORLD quot   quot IM quot   quot LEAVING quot   quot U quot   quot TODAY quot    let str    GOODBYE CRUEL WORLD IM LEAVING U TODAY  let matches        function recurse str  matches        let regex           A-Z        gm     let m     while   m   regex exec str       null            matches unshift m 3           return str replace m 2                 return  quot bzzt  quot     while   str   recurse str  matches       quot bzzt  quot     console log  quot Matches   quot   JSON stringify matches    Note  If you were really going to use this  you would use the position of the match as given by the regex match function  not a string replace

User · Answer

After reading Byte Commander s answer  I want to introduce a tiny possible improvement   You can generate a regexp that will match either n words  as long as your n is predetermined  For instance  if I want to match between 1 and 3 words  the regexp      A-Z         A-Z           A-Z         will match the next sentences  with one  two or three capturing groups   HELLO LITTLE WORLD HELLO WORLD HELLO   You can see a fully detailed explanation about this regular expression on Regex101   As I said  it is pretty easy to generate this regexp for any groups you want using your favorite language  Since I m not much of a swift guy  here s a ruby example   def make regexp group regexp  count  3  delimiter         regexp str        group regexp       count - 1  times each do     regexp str          delimiter    group regexp        end   regexp str          return regexp str end  puts make regexp   A-Z         That being said  I d suggest not using regular expression in that case  there are many other great tools from a simple split to some tokenization patterns depending on your needs  IMHO  a regular expression is not one of them  For instance in ruby I d use something like str split      or str scan   A-Z

User · Answer

Just to provide additional example of paragraph 2 in the answer   I m not sure how critical it is for you to get three groups in one match rather than three matches using one group   E g   in groovy   def subject    HELLO THERE WORLD  def pat      A-Z     def m    subject    pat  m eachWithIndex  g i - gt    println  Match   i    g 1       Match  0  HELLO Match  1  THERE Match  2  WORLD

User · Answer

With one group in the pattern  you can only get one exact result in that group  If your capture group gets repeated by the pattern  you used the   quantifier on the surrounding non-capturing group   only the last value that matches it gets stored   You have to use your language s regex implementation functions to find all matches of a pattern  then you would have to remove the anchors and the quantifier of the non-capturing group  and you could omit the non-capturing group itself as well    Alternatively  expand your regex and let the pattern contain one capturing group per group you want to get in the result      A-Z      A-Z      A-Z

User · Answer

The key distinction is repeating a captured group instead of capturing a repeated group  As you have already found out  the difference is that repeating a captured group captures only the last iteration  Capturing a repeated group captures all iterations  In PCRE  PHP        w        Match 1  Group 1     0-5      HELLO Match 2  Group 1     6-11     THERE Match 3  Group 1     12-20    BRUTALLY Match 4  Group 1     21-26    CRUEL Match 5  Group 1     27-32    WORLD  Since all captures are in Group 1  you only need  1 for substitution  I used the following general form of this regular expression        RE       Example at regex101

User · Answer

I think you need something like this      b  HELLO THERE WORLD  re findall    w    b    Which in Python3 will return    HELLO    THERE    WORLD

[regex] How to capture multiple repeated groups?

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