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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Global Regular Expression matching in Ruby (using scan)

Regular expression 'engines' start at the left of an input string they're matching against, and counts are usually greedy, so by default they return "leftmost, longest" matches - which works for what users want in most cases.

However, sometimes you may want to work through all (non-overlapping) matches in a string - for example to pick up a series of email addresses or URLs from a line or block of text. In Ruby, you can achieve that through the scan method on a string. A single match:
  if myStringRecord =~ /\s*(\S{1,})@(\S+)\s*/
or changing that to a multiple or global match:
  myStringRecord.scan(/\s*(\S{1,})@(\S+)\s*/) do |tom,dick|
which is a loop populating the variables dick and tom.

Complete example [here]. Topic covered on our Ruby Courses.

Should you wish to match the shortest rather than longest alternatives, an additional ? character after the count(s) you want to vary should be added.
  "banana" =~ /a(.*)a/
  puts $1
  "banana" =~ /a(.*?)a/
  puts $1

outputs
  nan
  n


(written 2015-01-08)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R109 - Ruby - Strings and Regular Expressions
  [970] String duplication - x in Perl, * in Python and Ruby - (2006-12-07)
  [986] puts - opposite of chomp in Ruby - (2006-12-15)
  [987] Ruby v Perl - interpollating variables - (2006-12-15)
  [1195] Regular Express Primer - (2007-05-20)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
  [1588] String interpretation in Ruby - (2008-03-21)
  [1875] What are exceptions - Python based answer - (2008-11-08)
  [1887] Ruby Programming Course - Saturday and Sunday - (2008-11-16)
  [1891] Ruby to access web services - (2008-11-16)
  [2293] Regular Expressions in Ruby - (2009-07-16)
  [2295] The dog is not in trouble - (2009-07-17)
  [2608] Search and replace in Ruby - Ruby Regular Expressions - (2010-01-31)
  [2614] Neatly formatting results into a table - (2010-02-01)
  [2621] Ruby collections and strings - some new examples - (2010-02-03)
  [2623] Object Oriented Ruby - new examples - (2010-02-03)
  [2980] Ruby - examples of regular expressions, inheritance and polymorphism - (2010-10-02)
  [3424] Divide 10000 by 17. Do you get 588.235294117647, 588.24 or 588? - Ruby and PHP - (2011-09-08)
  [3621] Matching regular expressions, and substitutions, in Ruby - (2012-02-23)
  [3757] Ruby - a teaching example showing many of the language features in short but useful program - (2012-06-09)
  [3758] Ruby - standard operators are overloaded. Perl - they are not - (2012-06-09)
  [4505] Regular Expressions for the petrified - in Ruby - (2015-06-03)
  [4549] Clarrissa-Marybelle - too long to really fit? - (2015-10-23)


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Some other Articles
Interview conditions,and other instructions to staff
Refactoring Perl applications to give them a rosy future
Checking MySQL database backups have worked (not failed)
Cucumber example - test::unit, scenario outlines, datafile driven test
Global Regular Expression matching in Ruby (using scan)
Regression Testing my website - Cucumber and Watir
Guide exercise to help you learn Gherkin, Cucumber and Rspec
A booking that looks too good to be true? It probably is too good to be true!
Installing Cucumber on Ubuntu - cannot load such file -- mkmf (LoadError) message
Improved test in Cucumber with RSpec
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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