On Thu, 13 Jun 2013 08:56:56 -0500, Elardus Engelbrecht wrote: >John McKown wrote: > >>Questions: If I decide on making the above an array: What if STEM.2 doesn't >>exist? What if STEM.100 exists? > >Easy, if you refer to an UNASSIGNED stem item, the default value is 'empty' if >you try to refer to it. > Not so easy. It assumes that the assignment "hole. = 'empty'" has been performed, as in the example. And that 'empty' can't otherwise legitimately occur in the data.
>Do this on TSO to see (example from REXX Ref): > >/* rexx */ >hole. = "empty" >hole.9 = "full" >say hole.1 hole.mouse hole.9 > >Result: empty empty full > Rexx has the nice function, SYMBOL() to tell whether a variable has been assigned to. Many langages lack this (has PL/I anything similar?) I've struggled with an interface (in C, I believe; OCO) to an SQL DB which supplies an empty string as the value of any empty cell. This makes it impossible to distinguish between an empty cell and a cell containing a null string. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
