Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!elroy.jpl.nasa.gov!hacgate!ashtate!dbase!tomr
From: tomr@dbase.A-T.COM (Tom Rombouts)
Newsgroups: comp.databases
Subject: Re: Wildcard searches in dBASE -or- Clipper
Keywords: dBASE Clipper
Message-ID: <1991Feb8.170828.8844@dbase.A-T.COM>
Date: 8 Feb 91 17:08:28 GMT
References: <1991Feb6.002241.4960@oeo2.uucp>
Reply-To: tomr@dbase.UUCP (Tom Rombouts)
Distribution: usa
Organization: Ashton-Tate
Lines: 39

In article <1991Feb6.002241.4960@oeo2.uucp> greinkem@oeo2.uucp (Mark Greinke) writes:
>I hope somebody out there can help me.  I am trying to implement a
>wildcard indexed search under dBASE III+ (eventually to be compiled 
>using Clipper, Summer '87).  Is there a way to do this?  
>
>Basically if the user inputs a search string such as "BOGOTA" 
>it would find valid matches in "AMEMBASSY BOGOTA" and 
>                               "AMERICAN EMBASSY BOGOTA" and
>                               "AMB BOGOTA"
>

For the above simple example, the dBASE "$" operator could be used
as such:

   "BOGOTA" $ <character expression> 

   which would return .T. is "BOGOTA" were anywhere in the character
expression.  You could use UPPER() (or LOWER() ) on either or
both expressions to ignore the case of the letters.

Of course, the _real_ way to do this would be to code up a
regular expression matching routine in C or .ASM, and link
it in to either Clipper or the upcoming Ashton-Tate Professional
Compiler.  The source for GNU grep is readily available on the
net, and chapters 19 and 20 of Sedgewick's "Algorithms in C"
discuss the details of pattern matching theory.  (Less detailed,
but more readable than Knuth.)  Also, Blaise's "Power Search"
package provides an interesting example of this in .ASM code.

Finally, for quick and dirty work, there are several DOS AWK
packages, as well as Friendly Finder, Ask Sam or other text
retrieval utiliies that would likely work directly on a .DBF
type file.  (If not, you could first export the data to text
format.)

Hope this helps....


Tom Rombouts  Torrance 'Tater  tomr@ashtate.A-T.com  V:(213)538-7108