Re: [bug-gawk] gawk: questions:

[Andrew J. Schorr]

Hi Denis,

On Sat, Jan 12, 2013 at 07:07:28PM +0200, Denis Shirokov wrote:
> I have some questions
> 
> 1)Why:
> isarray(A[1]) - creates string element at A[1] if A was never defined
> as array nor string?
> BEGIN{
>       if ( 1 in A )                   print "A: is EXIST"
>       if ( isarray(A[1]) )            print "B: is Array"
>       if ( 1 in A )                   print "C: is EXIST" }
> prints:
> C is EXIST
> 
> This is not right. I just answer `A[1] is actually array?' - this
> question exactly means that element can be string or array or
> undefined - and if it's undefined - then it should be stay undefined.

Sorry, that's just not how it works.  In your second test, you should say:

   if ((1 in A) && isarray(A[1])) ...

Otherwise, your accessing A[1] creates the array element.
I think this is pretty well documented.  There is no need to extend
the language; you simply must take care to use the "in" operator to
test before accessing an array element.

Regards,
Andy