OpenEuphoria

RE: "if var!=-1 then" and "if not var=-1 then"

• Posted by CoJaBo <cojabo at suscom.net> Feb 24, 2004
• 496 views

Thanks, but can anyone explain why, with the same code, this only 
started happening now?

Travis Beaty wrote:
> 
> 
> Hello!
> 
> Looks like you need to check your operator precedence. I think what you 
> are 
> getting with 
> 
> not var = -1
> 
> is this ...
> 
> (not var) = -1
> 
> not this ...
> 
> not (var = -1)
> 
> 
> So, it's testing the value of (not var) against the value of -1.
> 
> Of course, I'm not real sure ... but a thought.
> 
> 
> ------------------------
> >From the Reference Manual:
> 
>  2.2.10 Precedence Chart 
> 
> The precedence of operators in expressions is as follows: 
> 
>         highest precedence:     function/type calls
> 
>                                 unary-  unary+  not
> 
>                                 *  /
> 
>                                 +  -
> 
>                                 &
> 
>                                 <  >  <=  >=  =  !=
> 
>                                 and  or  xor
> 
>         lowest precedence:      { , , , }
> 
>  
> Thus 2+6*3 means 2+(6*3) rather than (2+6)*3. Operators on the same line 
> above 
> have equal precedence and are evaluated left to right. 
> --------------------------
> 
> Travis W. Beaty
> Osage, Iowa.
> 
> 
> On Tuesday 24 February 2004 04:39 pm, CoJaBo wrote:
> >
> >
> > It there a differance between
> > if var!=-1 then
> > and
> > if not var=-1 then?
> >
> > On a program I was working on here is what happened:
> >
> > ?st--displayed 5
> > if not st=-1 then
> > puts(1,"Hello!")--didn't run
> > --bunch of other stuff was here, didn't run
> > end if
> >
> > Then I tried this to see what would happen:
> >
> > st=-1
> > ?st--displayed 5
> > if not st=-1 then
> > puts(1,"Hello!")--still didn't run
> > --bunch of other stuff was here,still didn't run
> > end if
> >
> > Then I tried this:
> >
> > ?st--displayed 5
> > if st!=-1 then
> > puts(1,"Hello!")--Displayed "Hello!"
> > --bunch of other stuff was here, ran fine
> > end if
> >
> > What is happening?!?!?
> 
>