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Can you use a boolean OR in an if statement?
Jesse Barnett
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Join date: 21 May 2006
Posts: 4,160
10-03-2006 12:32
Where did I go wrong here:

CODE

else if (message == "Add")
   {
       integer b = TRUE;
       integer m = TRUE;
       b = (llGetListLength(dest) > 20);				
       m = (llGetFreeMemory() < 200);
       if (!b ||  m )// Tests to see if either statement is true
       {
            llOwnerSay("You can not add any more destinations");
       }
       else    
       {
             llOwnerSay("What do you want to name this destination?");
              state adddest;
        }
     }
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From: someone
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Joannah Cramer
Registered User
Join date: 12 Apr 2006
Posts: 1,539
10-03-2006 12:38
From: Jesse Barnett
Where did I go wrong here:

CODE

       if (!b ||  m )// Tests to see if either statement is true

Order of operation. that statement says literally "if 'not b' OR m" because OR is near the very bottom of operation chain (http://www.lslwiki.com/lslwiki/wakka.php?wakka=operators)

You can enforce correct order with:

if( !( b || m ) ) ...

or easier to read:

if( (b == TRUE) || (m == TRUE) ) ...
Don Misfit
Registered User
Join date: 1 Jun 2006
Posts: 60
10-03-2006 13:06
Jesse --- While Joannah's explanation of Order of operation is correct, I think you have a logic error there...

Your comment indicates that you are looking to see if "either statement is true," but the conditional:

CODE
 if ( !b || m )
is really saying:

if b is FALSE OR if m is TRUE

I think what you want is simply:

CODE
 
if ( b || m ) // Tests to see if either statement is true

Don
Jesse Barnett
500,000 scoville units
Join date: 21 May 2006
Posts: 4,160
10-03-2006 14:06
Thank you Don, Yep I played with it some and came up with:

CODE

if ( !b || !m )


and it worked and then just I changed the TRUE's to FALSE's and changed "if" to the way you have it. Just took a little nudge and some brain exercise:-)
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ed44 Gupte
Explorer (Retired)
Join date: 7 Oct 2005
Posts: 638
de Morgan
10-03-2006 18:49
for what it is worth,
CODE
(!a || !b) == !(a && b)

and
CODE
(a || b) == !(!a && !b)

sometimes helps to use alternate version

So
CODE
( !b || !m )

could become
CODE
!(b && m )

and if you invert the if/else clauses you would use
CODE
(b && m )

which is probably the easiest to follow