ruby print selected lines of text in between 2 strings

Question

i'm trying to get a group of text in between 2 strings in ruby, and i can't seem to get the right method or use the right regex.

text:

<html>
<body>

<!-- begin posts --> 

<h1>all kinds of html<h1>
<p> blah blah </p>
<p> i've been working on this forever </p>

<!-- end posts --> 

</html>
</body>

and i just want to get everything from  to  , inclusive, and save that block of text in a text file.

i figured out how to print the line in the beginning:

File.open("index.html").each_line do |line|
body.each {|line| puts line if line =~ /<!-- begin/}

but not the lines after up and until the last string.

i have a rubular here http://rubular.com/r/0W9QDpMGkM where i haven't been able to figure out anything.

thanks everyone in advance.

Answer 1

Don't do it line by line, just slurp the whole thing into a string and rip it apart:

s    = File.read('index.html')
want = s.match(/<!-- begin posts -->(.*)<!-- end posts -->/m)[1]

And now everything between your markers is in want . Don't forget the m modifier on the regex.

While you're mangling your input you can strip out the stray leading and trailing whitespace too:

want = s.match(/<!-- begin posts -->(.*)<!-- end posts -->/m)[1].strip

As Tudor notes below, you might want to use a non-greedy (.*?) for the group if you think there is any chance of multiple  markers; doesn't hurt to be a little paranoid when they really are you to get you.

References:

File.read (actually IO.read )
String#match
String#strip

UPDATE : the match method on a string returns a MatchData object. The array access operator :

... mtch[0] is equivalent to the special variable $& , and returns the entire matched string. mtch[1] , mtch[2] , and so on return the values of the matched backreferences (portions of the pattern between parentheses).

Is used to access the matching parts. There's only one group in the regex so [1] gets you the contents of that group without the surrounding HTML comment delimiters.

Answer 2

try with:

printing = false
File.open("index.html").each_line do |line|
  printing = true if line =~ /<!-- begin/      
  puts line if printing
  printing = false if line =~ /<!-- end posts/
end

Answer 3

File.readlines(ARGV[0]).each do|line|
  if line =~ /<!-- begin posts -->/ .. line =~ /<!-- end posts -->/     
    puts line
  end
end

ruby print selected lines of text in between 2 strings

Question

3 answers

solution1
8 ACCPTED 2011-07-09 04:55:12

solution2
2 2011-07-09 04:50:07

solution3
0 2014-03-21 17:00:25

ruby print selected lines of text in between 2 strings

Question

3 answers

solution1 8 ACCPTED 2011-07-09 04:55:12

solution2 2 2011-07-09 04:50:07

solution3 0 2014-03-21 17:00:25

solution1
8 ACCPTED 2011-07-09 04:55:12

solution2
2 2011-07-09 04:50:07

solution3
0 2014-03-21 17:00:25