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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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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.

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I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
String formatting in Lua - string.format as a wrapper for sprintf

Lua is a small language - and so for some elements of its functionallity it uses wrappers around underlying C functions rather than re-implementing and duplicating logic. A good example is the string.format function which in essence is a wrapper around sprintf.

For example:
  thing = string.format("> %8.2f > %d",person[1],person[2])
  print (thing)


• using the string template which is the first paramater of the function call, substitute a floating point number 8 characters wide, of which two characters are afer the decimal point, into the first place holder and a decimal (base 10) integer as many characters wide as it needs to be into the second placeholder, and store the resulting string into a variable called thing

• then output the contents of the variable called thing, adding a new line onto the end.

This may feel a bit clunky and old fashioned but it works very well. And the Lua wrapper saves you all the extra work of declaring and allocating memory for the variable called thing, adding the new line, ensuring you have space for a null terminator too. And it save you the heartache of scratching your head while you debug if you have forgotten to allocate the memory of leave space for the terminator.

Another very simple and logical solution from Lua ... we teach Lua [descriptions] ... and there's an example from a past course with some more formatting examples [here]. Further string format examples [here].
(written 2014-05-07)

 
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)
  [2348] Finding literals rather than patterns in Lua - (2009-08-11)
  [2357] Checking if the user has entered a number (Lua) - (2009-08-13)
  [2500] Dynamically formatting your results (Lua) - (2009-11-10)


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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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