Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
Python, Lua, Tcl, C and C++ training - public course schedule [here]
Private courses on your site - see [here]
Please ask about maintenance training for Perl, PHP, Java, Ruby, MySQL and Linux / Tomcat systems
 
The goto statement in Lua

In the past there was considerable debate in academia and industry on the merits of the use of goto statements, and indeed Lua didn't have them until release 5.2. Well used in Lua, they can provide an escape from inner loops, jumping to a label using a ::label:: format. For example:

  for z=1,10 do
     for y=1,10 do
        for x=1,10 do
           if x^2 + y^2 == z^2 then
              print('found a Pythagorean triple:', x, y, z)
              goto done
           end
        end
     end
  end
  ::done::


You cannot jump into an inner scope which includes local variables, and there are some further (sensible) limitations. This use of the goto to get out of multiple nested loops save you a whole series of nested checks or booleans.

There's a complete example showing sample output too [here].
(written 2012-04-06, updated 2012-04-07)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U103 - Lua - Conditionals and loops
  [4574] repeat until in Lua - a one or more rather than a zero or more loop - (2015-11-05)
  [4323] Learning to program - Loop statements such as while - (2014-11-22)
  [4322] Learning to Program - the conditional statement (if) - (2014-11-21)
  [4272] Lazy operators in Lua - what they mean, and examples - (2014-05-05)
  [3558] Python or Lua - which should I use / learn? - (2011-12-21)
  [3397] Does a for loop evaluate its end condition once, or on every iteration? - (2011-08-18)
  [2455] Lua examples - coroutines, error handling, objects, etc - (2009-10-15)
  [2454] For loops in Lua - (2009-10-14)
  [2351] Ternary operators alternatives - Perl and Lua lazy operators - (2009-08-12)
  [1738] Clean code, jump free (Example in Lua) - (2008-08-06)
  [1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
  [1685] Short circuit evaluation (lazy operator) in Lua - (2008-06-22)

U198 - New in Lua 5.2
  [3690] Changes in Lua 5.2 - Garbage Collection - (2012-04-08)
  [3687] Binary / bitwise operations in Lua with the standard bit32 library - (2012-04-06)
  [3683] Weak references in Lua - what are they, and why use them? - (2012-04-04)


Back to
Programming Standards in Lua
Previous and next
or
Horse's mouth home
Forward to
Binary / bitwise operations in Lua with the standard bit32 library
Some other Articles
Can I cycle or ride my mobility scooter on the pavement?
Shopkeepers take an Easter break too
The goto statement in Lua
Programming Standards in Lua
Once upon a Maundy Thursday
Melksham Business Newsreel
Kicking up a stink, the Victorian way?
4755 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page


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.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2017: 404 The Spa • Melksham, Wiltshire • United Kingdom • SN12 6QL
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/3686_The ... n-Lua.html • PAGE BUILT: Sat May 27 16:49:10 2017 • BUILD SYSTEM: WomanWithCat