Tcl regular expression string matching

Question

I have a list of strings like this one:

A/B/C/P/E

I want to use a regex to capture only up to

A/B/C/P

and ignore the trailing /E

I tried using:

set mystring {A/B/C/P/E}
regex -nocase -- {(.*)\/\S+} $myString match
puts $match

but

puts $match 

prints

A/B/C/P/E

What am I doing wrong?

Answer 1

an alternative: split the string, take all but the last element, re-join the list:

% set mystring {A/B/C/P/E}
A/B/C/P/E
% set new [join [lrange [split $mystring /] 0 end-1] /]
A/B/C/P

Answer 2

You are doing a couple of things wrong actually.

1. You have a string named $mystring, but you are using $myString in your function.

2. The syntax for regexp is:

   regexp ?switches? exp string ?matchVar? ?subMatchVar subMatchVar ...?
   

   So you if you want the submatch, you need to use another variable.

Now, to make everything cleaner, you can use:

set myString {A/B/C/P/E}
regexp -- {(.*)/\S+} $myString -> match
puts $match
# => A/B/C/P

codepad demo

You don't need to escape the forward slash, and if you don't have character that have casing in your regex, you don't need the -nocase flag.

The whole match is stored in the variable named -> and the first submatch in match.