OpenEuphoria

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

• Posted by "Elliott S. de Andrade" <quantum_analyst at hotmail.com> Feb 24, 2004
• 509 views

>From: CoJaBo <cojabo at suscom.net>
>Subject: "if var!=-1 then"  and "if not var=-1 then"
>
>It there a differance between
>if var!=-1 then
>and
>if not var=-1 then?
>

  Yes. They have different precedence levels. not is higher than =, so it's 
really doing this:

  if (not var) = -1 then

which, if var equals -1 then it will do:

  (not var) = -1
  (not -1) = -1
  0 = -1 -> false

>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?!?!?
>