Re: for loop 'bad math expression'

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

On 2024-02-03 18:05, Lawrence Velázquez wrote:

> 	% var=abc
>
> 	% unset abc
> 	% print -- $((var))
> 	0
>
> 	% abc=1
> 	% print -- $((var))
> 	1
>
> 	% abc=1+1
> 	% typeset -p abc
> 	typeset abc=1+1
> 	% print -- $((var))
> 	2
>
> 	% abc='1.0 * PPID / SECONDS - RANDOM'
> 	% typeset -p abc
> 	typeset abc='1.0 * PPID / SECONDS - RANDOM'
> 	% print -- $((var))
> 	-10080.313725490196
>
>     
    
    That astonishes me.  I've never heard of any such thing.  Nobody
    tells you these things.
    
    % var=abc; print -- $var
    abc
    
    % abc=1; print -- $((var))
    1
    
    # abc was a string, now it's the name of an integer:
    % let abc+=3; print -- $((var))
    3
    
    # var still wants to be scalar:
    % var+=3; print -- $var 
    abc3
    
    # So once var has been touched directly the link to abc is broken:
    % abc+=2; print -- $((var))
    0
    
    % abc=2; print -- $((var))
    0
    
    ... I suppose there's a good reason for it, but that leaves me
    dumbfounded. 
    
    % Sonnet_1='From_fairest_flowers_we_desire_increase'; print --
    $Sonnet_1
    From_fairest_flowers_we_desire_increase
    
    % From_fairest_flowers_we_desire_increase=1        
    
    % print -- $((Sonnet_1))
    1
    
    ... ok ... 
    
    Anyway, the lesson is just not to assign a glob expansion to an
    integer.  Never, ever.  Sorry for the trouble gentlemen.