How can regexp choose the smallest possible area?

[firelex]

Hello, all!
My problem is:
I have a string like "Title:zuiop:asddf:asdf:dd".
I wanted to regexp it so, that [tt]"Title"[/tt] and the rest of the string were put into two separate variables.
BUT the point is : regexp always tries to select the largest possible range from the string. Here is my regexp:
[tt]
set temp "Title:zuiop:asddf:asdf:dd"
regexp {^(.*)\.*)$} $temp all v1 v2
[/tt]
It divides into "Title:zuiop:asddf:asdf" and "dd" and not [tt]Title[/tt] and [tt]zuiop:asddf:asdf:dd[/tt]!!!

This one doesn't work also :
[tt]regexp {^([^\:].*)\.*)$} $temp all v1 v2[/tt]

Any ideas? Thanks in advance

 

[marsd]

regexp "^(\[a-zA-Z\]+):(.*)" $name all one two
1
(bin) 15 % puts $one ; puts $two
Title
zuiop:asddf:asdf:dd

regexp "(\[a-zA-Z0-9\]+):(.*)" $name all one two
1
(bin) 37 % puts $one ; puts $two
Title
zuiop:asddf:asdf:dd

 

[AviaTraining]

You almost had it with your second attempt. The problem was that your pattern [tt][ignore]([^\:].*)[/ignore][/tt] tried to match a single, non-colon character followed by 0 or more of any other characters. You wanted [tt][ignore]([^:]*)[/ignore][/tt] to match 0 or more non-colon characters. Also, as a minor note, the last [tt]$[/tt] is superfluous, as the preceding [tt](.*)[/tt] will already match as many characters as possible, all the way to the end. As is the leading [tt]^[/tt], as a regular expression matches as early in a string as possible. Thus, your streamlined regexp pattern is:

regexp {([^:]*):(.*)} $str all v1 v2

By the way, some people might suggest using the non-greedy quantifiers, introduced in Tcl 8.1, which match as few characters as possible while still fulfilling the entire match. The only problem is that in Tcl, mixing greedy and non-greedy quantifiers is very tricky and therefore advised against. For example, the following fails, because it turns out the the first non-greedy quantifier ends up making the entire regular expression non-greedy:

[tt]% regexp {(.*?).*)} $str all v1 v2
1
% set v1
Title
% set v2
% [/tt]

Using a non-greedy quantifier in this case does turn out to need the [tt]$[/tt] anchor:

[tt]% regexp {(.*?).*)$} $str all v1 v2
1
% set v1
Title
% set v2
zuiop:asddf:asdf:dd[/tt]


- Ken Jones, President, ken@avia-training.com
Avia Training and Consulting,

http://www.avia-training.com

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[firelex]

Thanks Avia!
Thanks marsd. Your regexp would also work, but I don't know if there any [\;\-\.] and so on could also be present in that string.