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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.
Finding literals rather than patterns in Lua

Lua's string.find looks for a PATTERN ... it's not as big an sophisticated as a regular expression match (but then it's got nothing like as big a footprint!), but neither is it a literal match. So if I want to search a string for - literally - a ".", I need to protect it. I can do this either with a % character, or by providing an extra true parameter to my find, meaning "I really want literals"

Let's look for a dot:

pos,posend = string.find(sed,".",at,true)
if not pos then break end


string.find returns both the start and the end character numbers of the match; in the case of a single literal character match such as mine here, the two values will be identical and indeed I could have left out ,posend save for my desire to provide an illustration.

Complete example source here, courses on the subject here.
(written 2009-08-11)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U104 - Lua - Strings and the String library.
  [1744] Lua examples, Lua Courses - (2008-08-08)
  [2357] Checking if the user has entered a number (Lua) - (2009-08-13)
  [2500] Dynamically formatting your results (Lua) - (2009-11-10)
  [4274] String formatting in Lua - string.format as a wrapper for sprintf - (2014-05-07)


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Ten years in Melksham - looking forward to ten more.
Businesses effected by road works in Melksham
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
World Flags in your PHP pages
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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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