https://www.cs.sjsu.edu/~mak/CS185C/KnuthStructuredProgrammingGoTo.pdf
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Bob Bridges [robhbrid...@gmail.com] Sent: Saturday, June 6, 2020 1:53 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: COBOL Question Oh, you need an END-IF even for a single-statement IF? I forgot; I've been thinking in REXX too long. In that case you're close; I guess I really meant PERFORM 1050-LOOP THRU 1050-EXIT VARYING JC FROM 1 BY 1 TO 99 1050-LOOP. IF X > 999 GOTO 1050-EXIT END-IF. IF FIRST-NAME = "ROBERT" GOTO 1050-EXIT END-IF. IF TYPE <> 195 GOTO 1050-EXIT END-IF. IF NOT SO-ON GOTO 1050-EXIT END-IF. IF NOT SO-FORTH GOTO 1050-EXIT END-IF. [do such and such] 1050-EXIT. I'm happy to hear someone else admit that a GOTO is conceivable under ~any~ circumstances. In my old shop I argued for GOTOs in three very strictly limited circumstances, the other two being end-of-section and end-of-program. Some languages allow for this by including some flavor of "leave" statement; all I want to do with a GOTO is to simulate that part of structured programming. But at the particular shop I have in mind, none of that could be contemplated, because all GOTOs are evil. --- Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 /* Law #21 of combat operations: The important things are always simple; the simple things are always hard. */ -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Joe Monk Sent: Saturday, June 6, 2020 04:49 I think what you mean is this: PERFORM 1050-LOOP THRU 1059-EXIT VARYING JC FROM 1 BY 1 UNTIL JC = 99 END-PERFORM 1050-LOOP. IF FIRST-NAME NOT = "ROBERT" GO TO 1059-EXIT END-IF IF TYPE NOT = 195 GO TO 1059-EXIT END-IF IF NOT SO-ON GO TO 1059-EXIT END-IF IF NOT SO-FORTH GO TO 1059-EXIT END-IF PERFORM 1050-SUCH-AND-SUCH END-PERFORM 1059-EXIT. EXIT. In structured programming, it is perfectly acceptable to use GO TO within a paragraph. It is NOT acceptable to use GO TO outside of a paragraph. --- On Sat, Jun 6, 2020 at 12:42 AM Bob Bridges <robhbrid...@gmail.com> wrote: > I realize this is a bit of a change in subject (and it's not as if we need > yet another one), but I avoid this construction. My phobia is based on an > extreme example: In their zeal never to use GOTOs, I've frequently seen > programmers write paragraphs like this: > > PERFORM 1050-LOOP VARYING JC FROM 1 BY 1 TO 99 > > 1050-LOOP. > IF X < 1000 > IF FIRST-NAME NOT = "ROBERT" > IF TYPE = 195 > IF SO-ON > IF SO-FORTH > EXECUTE 1050-SUCH-AND-SUCH > END-IF > END-IF > END-IF > END-IF > END-IF > > Gives me a headache to try to evaluate that. Much better, in my opinion, > to introduce ONE LOUSY "GOTO EO-PARAGRAPH" like this: > > PERFORM 1050-LOOP THRU 1059-LOOP VARYING JC FROM 1 BY 1 TO 99 > > 1050-LOOP. > IF X > 999 GOTO 1059-LOOP. > IF FIRST-NAME = "ROBERT" GOTO 1059-LOOP. > IF TYPE <> 195 GOTO 1059-LOOP. > IF NOT SO-ON GOTO 1059-LOOP. > IF NOT SO-FORTH GOTO 1059-LOOP. > EXECUTE 1050-SUCH-AND-SUCH > 1059-LOOP. > > Keep in mind I haven't programmed in COBOL since Y2K; I had to look up the > syntax, I probably got part of it wrong nonetheless, and I'll bet there are > easier ways to do it nowadays. In REXX, for example, they have the ITERATE > statement: > > do jc=1 to 99 > if x>99 then iterate > if firstname='ROBERT' then iterate > if type<>195 then iterate > if \soon then iterate > if \soforth then iterate > call suchandsuch > end > > However you do it, I vastly prefer skip-to-next-item over nested Ifs. But > I confess that one single nested IF is not going to give me a headache; I > just react when I see one. Not your fault :). > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On > Behalf Of Gibney, Dave > Sent: Friday, June 5, 2020 16:17 > > Using OP > IF TVOLL (IND1) NOT = HIGH-VALUE > AND SMOD (IND1) = 'B' OR 'R' > > I would do > IF TVOLL (IND1) NOT = HIGH-VALUE > IF SMOD (IND1) = 'B' OR 'R' > Do the stuff ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
