Re: [bug-gawk] Indexing Arrays with number which have leading zero behaves unexpected

[Andrew J. Schorr]

Hi,

On Sun, Jun 03, 2018 at 09:54:43AM +0000, Kolbe, Wulf wrote:
> please find enclosed a small program which shows an effect during indexing 
> arrays with numbers which have leading zeros.
> It behaves at least unexpected for me, because of the behavior changes during 
> increasing the index number.
> If you run all numbers from 000-to255, then it works between 000-064, then 
> there is a gap of approx. 16 places and then it works again.
> 
> BEGIN{
> B[04]=2; printf("%d\n",B[4]);printf("%d\n",B[04]);
> B[064]=42; printf("%d\n",B[64]);printf("%d\n",B[064]);
> }
> 
> This effect was found on CoCalc Clouds gawk 4.1.3 but also verified on a lot 
> of older versions.
> The leading zeros were written to visually inspect lists with values like 
> palette definitions and there the effect shows as funny gab in the palette.

What effect are you talking about? What is your expected behavior, and
how does that compare to what actually happens?

There are two things to keep in mind here:

1. All array subscripts are strings.
   
https://www.gnu.org/software/gawk/manual/html_node/Numeric-Array-Subscripts.html

2. Numerical constants that start with "0" are considered to be octal values.
   
https://www.gnu.org/software/gawk/manual/html_node/Nondecimal_002dnumbers.html

I think some combination of these two factors should probably explain the
behavior you are seeing. If not, then there is a bug.

For example, using current gawk 4.2.1:

bash-4.2$ gawk 'BEGIN {B[064] = 42; for (i in B) print i, typeof(i)}'
52 string

Can you please explain further what you think is not working correctly?

Regards,
Andy