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Tcl / regsub - changing a string and using interesting bits
Regexp matches a string to a regular expression, and regsub goes one further in that it replaces the found string with something else, saving the transformed output into a new variable. But what if I want the output pattern to include part of the string that was matched? I can refer to the "interesting bits" using \1, \2, etc, if I wish.
Example:
# In Tcl,
# regub needle haystack newneedle saveithere
#
# Refer to matches in the newneedle via \1
# Example - to surround dogs, cats and rabbits with !s
#
regsub -all (cat|dog|rabbit) "The cat and dog and budgie" \
{!\1!} result
puts $result
Results:
earth-wind-and-fire:~/oct07/camb grahamellis$ tclsh rsd
The !cat! and !dog! and budgie
earth-wind-and-fire:~/oct07/camb grahamellis$ (written 2007-10-27, updated 2007-10-30)
Associated topics are indexed under T205 - Tcl/Tk - String Handling in Tcl [3576] Tcl - apparently odd behaviour of string trimleft - (2012-01-13) [3285] Extracting data from a string / line from file - Tcl - (2011-05-10) [3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04) [2472] split and join in tcl and expect - (2009-10-23) [1601] Replacing the last comma with an and - (2008-04-04) [1403] Square Bracket protection in Tcl - (2007-10-23) [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25) [779] The fragility of pancakes - and better structures - (2006-06-26) [404] How to check that a string contains a number in Tcl - (2005-08-06) T247 - Tcl/Tk - Advanced Regular Expressions [1613] Regular expression for 6 digits OR 25 digits - (2008-04-16) [1412] Sparse and Greedy matching - Tcl 8.4 - (2007-10-27) [1336] Ignore case in Regular Expression - (2007-09-08) [1305] Regular expressions made easy - building from components - (2007-08-16) [1195] Regular Express Primer - (2007-05-20)
Some other Articles
What we teach - expained for the non-technicalThe little gestures that can really countBuffering of inputs to expect, and match orderTcl / regsub - changing a string and using interesting bitsWhat is Expect?Wireless hotel tips - FTP and Skype connections failingReading from another process in Tcl (pipes and sockets)Away or home - which do I prefer?Sorting in Tcl - lists and arrays
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