RegEx How to find text between two strings

Question

I have this text

XXX
text 
XXX

XXX
text 
XXX

XXX
text 
XXX

and i want to capture the text between the XXX and XXX. (i am trying to get chapters out from a book )

 /XXX.*XXX/

This will capture the first begin and the last end

 /XXX.*?XXX/

This will skip every second chapter

Thanks ahead Barak

what regexp flavour/tool are you using?

Fredrik Pihl
– Fredrik Pihl

2011-09-09 11:29:57 +00:00
Commented Sep 9, 2011 at 11:29 — Fredrik Pihl
– Fredrik Pihl, Commented Sep 9, 2011 at 11:29

Bohemian · Accepted Answer · 2011-09-10 03:40:39Z

4

If you text contains line feeds (\n) you'll need to add the "dot matched newline" switch to your regex, as well as making your match "non greedy":

/(?s)XXX.*?XXX/

Edited: Thanks to Alan's comment - I had the wrong switch: (?s) is correct

edited Sep 10, 2011 at 3:40

answered Sep 9, 2011 at 11:29

Bohemian♦

427k103 gold badges603 silver badges750 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Alan Moore Over a year ago

Multiline mode alters the behavior of the anchors, ^ and $, so it would be useless here. Perhaps you're thinking of "single-line" or "DOTALL" mode, which enables the . to match linefeeds.

daGrevis Over a year ago

To work with reg-exes, you must know reg-exes. To code, you just know how to code. :)

Fredrik Pihl · Accepted Answer · 2011-09-09 11:31:54Z

2

Solution using sed

$ sed -n '/XXX/,/XXX/{n;p}' text
text 

text 

text

answered Sep 9, 2011 at 11:31

Fredrik Pihl

45.9k7 gold badges89 silver badges133 bronze badges

Comments

Adam Jurczyk · Accepted Answer · 2011-09-09 11:45:55Z

1

If this XXX strings are always in separate lines, i would suggest simple iterating through lines and picking it 'by hand'. It should be faster than multi-line regexp.

python :

delim = "XXX"
inside = False
lines = []
idx = 0
for line in file:
    if line.strip() == delim:
        inside = not inside
        if inside: lines.append([])
        else: idx += 1
    elif inside:
        lines[idx].append(line)

edited Sep 9, 2011 at 11:45

answered Sep 9, 2011 at 11:35

Adam Jurczyk

2,13112 silver badges16 bronze badges

Comments

Alan Moore · Accepted Answer · 2011-09-09 15:18:26Z

0

Your description doesn't really match your examples. If XXX is supposed to represent a chapter heading, there would only be one at the beginning of each chapter. To detect the end of a chapter, you would need to do a lookahead for the next chapter heading:

/XXX.*?(?=XXX)/s

That should work for all but the last chapter; to match that you can use \z, the end anchor:

/XXX.*?(?=XXX|\z)/s

It really would help if we knew which regex flavor you're using. For example, in Ruby you would have to use /m instead of /s to allow . to match linefeeds.

answered Sep 9, 2011 at 15:18

Alan Moore

75.6k13 gold badges110 silver badges161 bronze badges

Collectives™ on Stack Overflow

RegEx How to find text between two strings

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related