AA of AAs -- ArrayBoundsError

[Matti Niemenmaa]

nobody wrote:
> Matti Niemenmaa wrote:
>> nobody wrote:
>>> The following code results in an ArrayBoundsError with my v1.015
>>> compiler:
>>>
>>>   typedef size_t IA;
>>>   typedef size_t IB;
>>>   typedef uint V;
>>>
>>>   void main(char[][] args)
>>>   {
>>>     V[IB] [IA] test;
>>>     test[cast(IA) test.length]
>>>       [cast(IB) test[cast(IA) test.length].length] =
>>>     cast(V) (test.length * test[cast(IA) test.length].length);
>>>   }
>>
>> The problem is on the right hand side of the assignment, namely on the
>> access
>> test[cast(IA) test.length]. The AA test is empty, so retrieving any
>> element will
>> fail with an ArrayBoundsError.
>>
>> Assign test[1][1] = something; first, and then it will work. (1, because
>> test.length will be 1 after the assignment.)
>>
> 
> I really messed up the example. You are correct that my example should
> not work. However, both the following add functions fail when I think
> they shouldn't:
> 
>   import std.stdio;
> 
> 
>   typedef size_t I;
>   struct Si { uint val; }
>   struct Sa
>   {
>     Si[I][I] table;
> 
>     void add(I i, Si si)
>     {
>       table[i][cast(I) table[i].length] =  si;
>     }
>   }

This is essentially the same case as your original example. table[i].length
results in an error because table[i] does not exist yet.

>   struct Sb
>   {
>     Si[][I] table;
> 
>     void add(I i, Si si)
>     {
>       if(table[i] is null)
>         table[i] = new Si[0];
> 
>       table[i].length = table[i].length + 1;
>       table[i][table[i].length - 1] = si;
> 
>     }
>   }

As above, "if (table[i] is null)" results in an error because table[i] does not
exist yet. What would, however, work is "if (!(i in table))". (You might have
noticed this if you would have output the error instead of just "Sb failed": the
ArrayBoundsError is on the line where the if statement is.)

BTW, you should post these on the digitalmars.D.learn newsgroup unless you're
100% sure they're bugs.

-- 
E-mail address: matti.niemenmaa+news, domain is iki (DOT) fi