Re: string compares with 'wildcards' in rpgiv

On Fri, 4 Oct 2002, Booth Martin wrote:
>
> what am I missing?  Why wouldn't the %Scan BIF work?  {Left if Position =1}
> {Middle if Position > 1 And  Position < (%len -start)} Else  {right }
>

The %SCAN BIF would work if you only wanted EXTREMELY SIMPLE pattern
matching.   To do something even close to the power of even the most
basic regular expressions would take thousands of lines of code.

Take the follow regular expression:

       "^A[RP]2002040[1-7]"

That could be used to match a filename that started with either "AR" or
"AP" and had a name that ended with any date from the first to seventh of
april in 2002.   It wouldn't match something that was "BAR20020401"
however, even tho AR20020401 is a substring of it.   It wouldn't match
any other dates in april besides the 1st - 7th.  It would include both
AR and AP, but not AB or anything else.

Sure, you could write a routine to match that exact set of conditions.
But you couldn't write one generic enough to let the user enter any search
pattern he wanted, and produce any results he wanted to that level.

At least, you couldn't do it without spending a LOT of time writing the
routines and testing and debugging them.

With regular expressions, all that capability is there, available for you
to use, and at very little time or cost.

That's what you're missing.