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. |
Sparse and Greedy matching - Tcl 8.4
Problem Analysis Once you have done a sparse or greedy count, all your following counts will also be sparse or greedy - this is a well documented bug in Tcl 8.4!
 Reminder ...
.* is a greedy match - any character and AS MANY AS POSSIBLE
.*? is a sparse match - any character but AS FEW AS POSSIBLE
set demo abc@def@ghi@jkl
#
# Correctly working greedy matches
regexp (.*)@(.*) $demo all first second
puts "$first and $second"
#
# Correctly working sparse matches
regexp (.*?)@(.*?) $demo all first second
puts "$first and $second"
#
# Both matches will be SPARSE here
regexp (.*?)@(.*) $demo all first second
puts "$first and $second"
#
# Both matches will be GREEDY here
regexp (.*)@(.*?) $demo all first second
puts "$first and $second"
Running that, we get:
earth-wind-and-fire:~/oct07/camb grahamellis$ tclsh spag
abc@def@ghi and jkl
abc and
abc and
abc@def@ghi and jkl
earth-wind-and-fire:~/oct07/camb grahamellis$
Suggested Work-around
You can emulate a sparse match by excluding the delimiter character from he group that you would be sparse matching, and using a greedy match.
Thus
regexp (.*?)@(.*) $demo all first second
can be rewritten as
regexp {([^@]*)@(.*)} $demo all first second
if you really needed sparse followed by greedy!
result:
abc and def@ghi@jkl (written 2007-10-27, updated 2011-03-01)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles T247 - Tcl/Tk - Advanced Regular Expressions [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25) [1195] Regular Express Primer - (2007-05-20) [1305] Regular expressions made easy - building from components - (2007-08-16) [1336] Ignore case in Regular Expression - (2007-09-08) [1410] Tcl / regsub - changing a string and using interesting bits - (2007-10-27) [1613] Regular expression for 6 digits OR 25 digits - (2008-04-16) [4205] Regular Expression Substitution - Tcl - (2013-11-12)
Some other Articles
Good, steady, simple example - Perl file handlingBetter technology makes for longer commutes?What we teach - expained for the non-technicalThe little gestures that can really countSparse and Greedy matching - Tcl 8.4Buffering of inputs to expect, and match orderWhat is Expect?Wireless hotel tips - FTP and Skype connections failingReading from another process in Tcl (pipes and sockets)
|
4759 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page
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).
|
|