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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.
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.
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)
  [1744] Lua examples, Lua Courses - (2008-08-08)
  [2509] A life lesson from the accuracy of numbers in Excel and Lua - (2009-11-21)
  [3917] BODMAS - the order a computer evaluates arithmetic expressions - (2012-11-09)
  [4569] Lua - changes to how integers and floats are handled - 5.2 to 5.3 - (2015-11-02)


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The indexed and hashed parts of a Lua table
Automatically initialising Lua variables the first time
Reading a data file and sensing EOF in Lua
World Flags in your PHP pages
Training Classes in other tongues
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ldning, Open Source dator spr[83][c2]åk
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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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