Re: [bug-gawk] Can a key in a array be deleted while the array is iterated?

[Andrew J. Schorr]

Hi,

On Sun, Jan 01, 2017 at 07:05:29PM -0600, Peng Yu wrote:
> I made the following function to intersect the keys of x1 and x2. The
> results is saved in x1. I am not sure it is OK to change an array
> while it is being iterated. Will the function always work? Thanks.
> 
> function arrkeyintersect(x1, x2,    k) {
>     for(k in x1) {
>         if(!(k in x2)) {
>             delete x1[k]
>         }
>     }
> }

It is safe. This should be apparent from the documentation:
   https://www.gnu.org/software/gawk/manual/html_node/Delete.html
It is also documented in the Posix awk specification:
   http://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html

   The delete statement shall remove an individual array element. Thus, the
   following code deletes an entire array:

   for (index in array)
       delete array[index]

In the future, when you have awk programming questions, please
post them to the comp.lang.awk usenet group. Please use this mailing
list for gawk bug reports only.

Regards,
Andy