Date:         Mon, 30 Nov 2009 16:39:03 +0100
Reply-To:     karma <dorjetarap@GOOGLEMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         karma <dorjetarap@GOOGLEMAIL.COM>
Subject:      Re: 4.29: How can I count the number of occurrences of a
Comments: To: kellogg <kel@log.co.uk>
In-Reply-To:  <DbSdnXbU-6CVqpDWnZ2dnUVZ_u6dnZ2d@earthlink.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi Kellog,

Without seeing your code / pattern, I can only guess that it's because
you didn't use positive/negative look ahead assertations. Assuming
that you are looking for negative values in your string that aren't
followed by characters, you can use the following pattern:

data _null_ ;
   str='-3 -5start -9 55 48 -2 23 -roger -76 4 14 -44 -nus- -189 - -44';
   pattern = prxparse('/-\d+(?![a-z])/') ;
   start=1 ;
   stop=length(str) ;
   call prxnext(pattern, start, stop, str, position, length);
      do while (position) ;
         found = substr(str, position, length);
         put found= position= length=;
         call prxnext(pattern, start, stop, str, position, length);
         end;
   run ;

log;
found=-3 position=1 length=2
found=-9 position=12 length=2
found=-2 position=21 length=2
found=-76 position=34 length=3
found=-44 position=43 length=3
found=-189 position=53 length=4
found=-44 position=60 length=3


2009/11/25 kellogg <kel@log.co.uk>:
> the lengths do not appear to be correct
>
> consider this string
>
> str='-3 -5start -9 55 48 -2 23 -roger -76 4 14 -44 -nus- -189 - -44';
>
> position=1 length=2 found=-3
>
> position=11 length=3 found=-9
>
> position=20 length=3 found=-2
>
> position=33 length=4 found=-76
>
> position=42 length=4 found=-44
>
> position=52 length=5 found=-189
>
> position=59 length=4 found=-44
>