Path: utzoo!attcan!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: F-PC Forth Tutorial
Message-ID: <1058.UUL1.3#5129@willett.UUCP>
Date: 1 Jun 90 03:45:59 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 72


 Date: 05-30-90 (22:56)              Number: 20 (Echo)
   To: JACK BROWN                    Refer#: NONE
 From: ROY RICE                        Read: NO
 Subj: LESSON3, EX3.11-12            Status: PUBLIC MESSAGE

 \ RARL3D.SEQ  ccontinuation of lesson 3
 \ (IN)  leaves a true flag if   a < x < b
 : (IN)  ( x a b --  flag )  ( JWB 28 09 88 )
          2DUP < NOT ABORT" Invalid interval."
          -ROT OVER < -ROT > AND ;

 \ Exercise 3.12
 \ Write definitions of [IN] (IN] and [IN) that do not use (IN) or
 \ each other!
 : [IN) ( x a b -- f )  \ true if a <= x < b
         2DUP < NOT ABORT" Invalid interval."
         -ROT OVER <= -ROT > AND ;

 : (IN] ( x a b -- f )  \ true if  a < x <= b
         2DUP < NOT ABORT" Invalid interval."
         -ROT OVER < -ROT >= AND ;


 : [IN]  ( x a b -- f ) \ true if a <= x <= b
         2DUP < NOT ABORT" Invalid interval."
                 -ROT OVER <= -ROT >=  AND ;

 \ ex 3.11 tests using my words
 : .F ( f -- ) \ display flag
         IF ." true    "  ELSE ." false   "  then  ;

 : TESTIN ( x a b -- ) \  test the interval words
         2DUP < NOT ABORT" Invalid interval."
         CR   3DUP
         SWAP  ." a = " .  4 SPACES
         SWAP  ." x = " .  4 SPACES ." b = " . CR
         ." (IN)    [IN)    (IN]    [IN] "     CR
         ." a<x<b   a<=x<b  a<x<=b  a<=x<=b"   CR
         3DUP (IN)  .F
         3DUP [IN)  .F
         3DUP (IN]  .F
              [IN]  .F   CR   ;
 comment:
 4 4 6 testin
 a = 4     x = 4     b = 6
 (IN)    [IN)    (IN]    [IN]
 a<x<b   a<=x<b  a<x<=b  a<=x<=b
 false   true    false   true
  ok
 4 5 6 testin
 a = 5     x = 4     b = 6
 (IN)    [IN)    ((IN]    [IN]
 a<x<b   a<=x<b  a<x<=b  a<=x<=b
 false   false   false   false
  ok
 5 4 6 testin
 a = 4     x = 5     b = 6
 (IN)    [IN)    (IN]    [IN]
 a<x<b   a<=x<b  a<x<=b  a<=x<=b
 true    true    true    true
  ok
 6 4 6 testin
 a = 4     x = 6     b = 6
 (IN)    [IN)    (IN]    [IN]
 a<x<b   a<=x<b  a<x<=b  a<=x<=b
 false   false   true    true
  ok
 comment;
-----
This message came from GEnie via willett through a semi-automated process.
Report problems to: uunet!willett!dwp or willett!dwp@hobbes.cert.sei.cmu.edu