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 07:05:28)

 T205 - Tcl/Tk - String Handling in Tcl
T247 - Tcl/Tk - Advanced Regular Expressions

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What we teach - expained for the non-technical
The little gestures that can really count
Sparse and Greedy matching - Tcl 8.4
Buffering of inputs to expect, and match order
Tcl / regsub - changing a string and using interesting bits
What is Expect?
Wireless hotel tips - FTP and Skype connections failing
Reading 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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