Re: Airthmetic confusion...

[Mike Hernandez <sequethin@gmail.com>]

On 5/16/05, Matthias Berndt <Berndt.Matthias@gmx.de> wrote:
> I don't know your problem, but these expression works fine here. Did you
> make something special before or in your startup-scripts?

Actually what happens is that the operation and assignment are
performed but the return code of the expression evaluates to 1, which
is an error. I tried on my machine and get the same results:

(mike@mhernandez)(24/pts)(04:45pm:05/16/05)-
(%:~)- (( x = 0 ))
(mike@mhernandez)(25/pts)(04:46pm:05/16/05)-
(%:~)- echo $?
1
(mike@mhernandez)(26/pts)(04:46pm:05/16/05)-
(%:~)- echo $x
0

If you set a variable to any integer other than 0, positive or
negative, the return code is 0, which is successful exit, for example:

(mike@mhernandez)(30/pts)(04:53pm:05/16/05)-
(%:~)- (( r = -5 ))
(mike@mhernandez)(31/pts)(04:53pm:05/16/05)-
(%:~)- echo $?
0

This occurs with a regular assignment as above, or if the assignment
contains some variables (as in x = b - 4, if b was 4 the return code
would be 1, yet the math is done and x is set to equal 0).

There must be a reason why assigning 0 to a variable is considered an
error (a reason which I could speculate about, but don't know for
sure).

Mike