If I have a list, I'm likely to want to present it comma separated for the most part, but with the word "and" between the last two elements.
"Cambridge, the M11, the M25, the M4, the A361 and Melksham" for example.
Lists or arrays can be joined in almost any language with a function called join or implode, and a parameter will allow you to specify that comma. But what about the "and"? A regular expression looking for a comma and replacing it with an "and" would just replace the FIRST comma. Solution - use a greedy "match anything" element at the start of the regular expression, thus matching the last comma. You can refer to $1 or \1 in your replacement string.
Want to see an example of that in use? Here is the algorithm coded in Tcl
set codez {SWI CPM MKM TRO WSB DMH WAR SAL}
puts $codez
set togo [join $codez ", "]
regsub {(.*),} $togo {\1 and} togo
puts $togo
And here is how it runs
Dorothy:mt2 grahamellis$ tclsh fbl
SWI CPM MKM TRO WSB DMH WAR SAL
SWI, CPM, MKM, TRO, WSB, DMH, WAR and SAL
Dorothy:mt2
Example written as a demonstration for delegates on the
Tcl and Expect course I am running at the moment.
(written 2008-04-04)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
T206 - Tcl/Tk - Lists [144] Tcl sandwich - lists in Tcl - (2004-12-08)
[463] Splitting the difference - (2005-10-13)
[781] Tcl - lappend v concat - (2006-06-27)
[1282] Stringing together Tcl scripts - (2007-07-29)
[1283] Generating traffic for network testing - (2007-07-29)
[1334] Stable sorting - Tcl, Perl and others - (2007-09-06)
[1402] Tcl - append v lappend v concat - (2007-10-23)
[1405] Sorting in Tcl - lists and arrays - (2007-10-24)
[2468] What are Tcl lists? - (2009-10-22)
[2472] split and join in tcl and expect - (2009-10-23)
[3285] Extracting data from a string / line from file - Tcl - (2011-05-10)
[3394] The difference between lists and strings - Tcl - (2011-08-16)
[3415] User defined sorting and other uses of callbacks in Tcl and Tk - (2011-09-02)
[3582] Tcl collections - lists, dicts and array - (2012-01-16)
[3583] Expanding a list of parameters in Tcl - {*} and eval - (2012-01-17)
[3618] lists and struct::list in Tcl - Introduction to struct::list and examples - (2012-02-18)
[4209] Lists in Tcl - fundamentals in a commented source code example - (2013-11-16)
[4454] Everything is a string - even a list - (2015-03-11)
[4455] Working out distance between places, using OS grid references and a program in Tcl - (2015-03-11)
T205 - Tcl/Tk - String Handling in Tcl [404] How to check that a string contains a number in Tcl - (2005-08-06)
[779] The fragility of pancakes - and better structures - (2006-06-26)
[943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
[1403] Square Bracket protection in Tcl - (2007-10-23)
[1410] Tcl / regsub - changing a string and using interesting bits - (2007-10-27)
[3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04)
[3576] Tcl - apparently odd behaviour of string trimleft - (2012-01-13)
[4205] Regular Expression Substitution - Tcl - (2013-11-12)
Q803 - Object Orientation and General technical topics - Regular Expressions - Extra Elements [1336] Ignore case in Regular Expression - (2007-09-08)
[1372] A taster PHP expression ... - (2007-09-30)
[1613] Regular expression for 6 digits OR 25 digits - (2008-04-16)
[1735] Finding words and work boundaries (MySQL, Perl, PHP) - (2008-08-03)
[1860] Seven new intermediate Perl examples - (2008-10-30)
[2909] Be gentle rather than macho ... regular expression techniques - (2010-08-08)
[3089] Python regular expressions - repeating, splitting, lookahead and lookbehind - (2010-12-17)
[3100] Looking ahead and behind in Regular Expressions - double matching - (2010-12-23)
[3516] Regular Expression modifiers in PHP - summary table - (2011-11-12)
[3650] Possessive Regular Expression Matching - Perl, Objective C and some other languages - (2012-03-12)
G996 - Well House Consultants - Newsletter Scripts [1001] .pdf files - upload via PHP, store in MySQL, retrieve - (2006-12-19)
[1066] Final, Finally and Finalize - three special words in Java - (2007-02-05)
[1123] mysqldump and mysqlrestore - (2007-03-30)
[1217] What are factory and singleton classes? - (2007-06-04)
[1321] Resetting session based tests in PHP - (2007-08-26)
[1387] Error logging to file not browser in PHP - (2007-10-11)
[1487] Efficient PHP applications - framework and example - (2007-12-28)
[1505] Script to present commonly used images - PHP - (2008-01-13)
[1665] Factory method example - Perl - (2008-06-04)
[1743] First class functions in Lua lead to powerful OO facilities - (2008-08-07)
[1813] Ajax - going Asyncronous and what it means - (2008-09-28)
[1954] mod_rewrite for newcomers - (2008-12-20)
[2046] Finding variations on a surname - (2009-02-17)
[2145] Using the internet to remotely check for power failure at home (PHP) - (2009-04-29)
[2259] Grouping rows for a summary report - MySQL and PHP - (2009-06-27)
[2360] Error Handling in Lua with assert and pcall - (2009-08-13)
[2433] Controlling, supressing, enabling PHP error messages - (2009-10-02)
[2539] Changing Images - (2009-12-17)
[3179] Oops - I typed ci not vi, and have lost my file ... - (2011-02-21)
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