2b87 The goto statement in Lua
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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 under
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)

U103 - Lua - Conditionals and loops
  [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)


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