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Automatically initialising Lua variables the first time

In Lua, you need to initialise variables before you perform arithmetic on them, but you CAN test them (and if they don't exist, they will return false).

For example, this code initialises a variable to 0 if it doesn't exist, or takes its current value, then adds 1 to it straight away before saving it tack in the same variable.

callcounter = (callcounter or 0 ) +1

See that in use in full source code, within a function where it in effect becomes a static variable , here
(written 2009-08-10, updated 2009-08-12)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U102 - Lua - Numbers and the Math library.
  [3917] BODMAS - the order a computer evaluates arithmetic expressions - (2012-11-09)
  [2509] A life lesson from the accuracy of numbers in Excel and Lua - (2009-11-21)
  [1744] Lua examples, Lua Courses - (2008-08-08)
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)


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