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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.
Reading a data file and sensing EOF in Lua

In Lua, the standard table io includes an io.open code element that lets you open a file. This returns a userdata to you (looks like a table but isn't - it's a C accessible structure) from which you can run the read code. Empty lines return an empty string (in Lua this is a TRUE value, unlike other languages), and at the end of file a nil is returned. See source code

You do need to write your reading loop as while true do, as you are not allowed to assign a value to a variable within the test condition - the = sign is not an operator in the same way that it is in other languages.

Covered on our Learning to Program in Lua course.
(written 2009-08-10)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U110 - Lua - Input / Output
  [1744] Lua examples, Lua Courses - (2008-08-08)
  [1841] Formatting with a leading + / Lua and Perl - (2008-10-15)
  [3558] Python or Lua - which should I use / learn? - (2011-12-21)


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Automatically initialising Lua variables the first time
Some other Articles
Finding literals rather than patterns in Lua
Dot, dot, dot in Lua - variable length parameter lists
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
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Training Classes in other tongues
Koulutus, Open Source tietokone kielill[83][c2]ä
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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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