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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
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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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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