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Re: stregex question [message #67221]

Tue, 21 July 2009 09:53

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

wlandsman wrote:
> I'd like to find the first "e" in a string that is not next to
> another "e"
>
> The solution
> stregex(s,"e[^e]|$") ;"e" followed by not "e" or at the end of the
> line
> doesn't work for the string st = 'see me' because it will find the
> second "e" in "see"
>
> The soluton
> stregex(s,"e{1}") ;Find one occurrence of "e"
> also finds the first "e" in "see" (Two occurrences is also one
> occurrence)
>
> In Perl it seems that one would use the "lookahead" option, but that
> doesn't seem to be available in stregex().
>
> (Actually I am looking for the first quote that is not part of a
> double quote, but I wanted to keep the example syntax simple.)
> Thanks, --Wayne

I would do something like:

IDL> pos = stregex(s, '([^e]e[^e])|(^e[^e])|(^e$)|([^e]e$)')
IDL> pos += strmid(s, pos, 1) ne 'e'

You have to add one to pos if either the [^e]e[^e] or [^e]e$ forms matched.

Mike
--
www.michaelgalloy.com
Associate Research Scientist
Tech-X Corporation

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[Message index]

		Re: stregex question By: Michael Galloy on Tue, 21 July 2009 09:53
		Re: stregex question By: JDS on Tue, 21 July 2009 17:19
		Re: stregex question By: wlandsman on Tue, 21 July 2009 10:58

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