[Tiny-cobol-users] Re: a problem with EVALUATE

[Arnold T. <arn...@wo...>]

John R. Culleton Morcombe wrote:
> 
> Message: 2
> From: "John R. Culleton" <jo...@we...>
> Organization: WexfordPress
> To: tin...@li...
> Subject: Re: [Tiny-cobol-users] A problem with EVALUATE
> Date: Fri, 19 Aug 2005 08:06:05 +0000
> Cc: Jim Morcombe <ro...@vi...>
> 
> On Friday 19 August 2005 07:50 am, Jim Morcombe wrote:
> 
>>Here is another cut down listing.
>>
>>It demonstrates what I believe to be a bug in the compiler concerning
>>the EVALUATE statement.
>>
>>When I compile it, I get the following error message:
>>
>>jim.cbl:    18: error: incompatible selection object, on or before '='
>>
>>Jim
>>
>>                      IDENTIFICATION DIVISION.
>>      2 000300 PROGRAM-ID.              rgmssch.
>>      3 001200 ENVIRONMENT DIVISION.
>>      4 001700
>>      5 001900 DATA DIVISION.
>>      6 002100 FILE SECTION.
>>      7 002300
>>      8 002500 WORKING-STORAGE SECTION.
>>      9
>>     10        01  LICENCE-DAYS              PIC 9(5).
>>     11
>>     12
>>     13
>>     14 019500 PROCEDURE DIVISION.
>>     15 020200 MAINLINE.
>>     16
>>     17            EVALUATE TRUE
>>     18                WHEN LICENCE-DAYS = ZERO
>>     19                     CONTINUE
>>     20            END-EVALUATE.
> 
> 
> 
> I am not familiar with such a construct. According to the books
> I have, (three at the moment) you EVALUATE FIELDNAME.
> 
> And then the following  WHEN statements are equivalent to
> IF FIELDNAME = (value) (executable statement) 
> ELSE IF....
> 
> The EVALUATE TRUE statement in your program does not refer to a field name
> but a condition-name. This in turn requires a level 88 appended
> to a field name in e.g., WORKING STORAGE. 
> 
> CONTINUE is used in an IF statement. I have not found it used in
> a EVALUATE statement.  
> 
> TRUE is not a field but a condition name attributed to a field
> that has an 88 statement like:
> 
>         O1  WS-ANOTHER-RECORD PICTURE X.
>             88 ANOTHER-RECORD VALUE "Y" FALSE "N".  
> 
> EVALUATE with WHEN statements is an alternative to the use of IF with 
> condition
> names. Don't mix the two.

Jim Morcombe's sample COBOL program is perfectly legal COBOL.  It 
compiles cleanly under Realia COBOL, the ANSI-85 "educational" version 
from about 1990.  Of course, it does nothing upon execution.

If you use the EVALUATE TRUE option, you can put pretty much any 
conditional statement you want in a WHEN clause.

With kindest regards,

-- 
http://arnold.trembley.home.att.net/