Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: All Sorts of Sorts
Message-ID: <617.UUL1.3#5129@willett.UUCP>
Date: 6 Mar 90 01:04:24 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 38

Category 3,  Topic 37
Message 31        Sun Mar 04, 1990
F.SERGEANT [Frank]           at 21:52 CST
 
 To Steve & Ian,

SP> : LOOP_DEMONSTRATION  ( n2 n1 -- ) SP> \ That is, both the inner and outer
loop limits are on the stack SP> \ before this word executes.  You could put
them there by fetching SP> \ from a couple of variables, or whatever other
means you like. SP>    1 DO        ( Takes n1 from param stack, puts in on
Rstack ) SP>       1 DO     ( Takes n2 from param stack, puts it on Rstack )
SP>           <SOMETHING>  ( whatever you want to execute ) SP>       LOOP SP>
LOOP  ;

  Nope, the above will not work (unless n1 is 1).  The 2nd & subsequent 
passes thru the outer loop will have no limit available on the stack  for the
inner loop.  You need a DUP after the 1st DO and a DROP after  the last LOOP.

 Also, I keep seeing these "1"s as beginning indexes for your loops in  these
messages.  Presumably you want to say something like  10 STARS  and have your
word STARS print ten of 'em.  If you define STARS with a  built-in index of 1,
you'd have to say 11 STARS to get 10 of 'em.  

   : STARS  ( #-of-stars-desired - )   0  DO   STAR   LOOP  ;
   or
   : STARS  ( 1-more-than-#-of-stars-desired  - )  1  DO STAR LOOP ;

 On the other hand, you might want to use a built-in index of 1 when  you plan
to use the index inside of the loop, eg for addressing a one  based array.  I
would think the more common situation would be to use a  zero based array, in
which case you would still use a starting index   of 1.  

 Any questions?  (By the way, I don't use DO LOOP anymore, just FOR  NEXT.)

  -- Frank
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