For 2023 (and 2024 ...) - we are now fully retired from IT training. We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
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)
Some other Articles
Printed Directories - the start of the updating seasonTernary operators alternatives - Perl and Lua lazy operatorsTen years in Melksham - looking forward to ten more.Businesses effected by road works in MelkshamFinding literals rather than patterns in LuaDot, dot, dot in Lua - variable length parameter listsThe indexed and hashed parts of a Lua tableAutomatically initialising Lua variables the first timeReading a data file and sensing EOF in LuaWorld 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.
Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).
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