Difference between "->" and "-->" in array access?

[syzygy]

Hi all,

Can someone give me a quick hint what the difference is between accessing the elements of array “my_array” in the style of “my_array->x”, and “my_array–>x”, resp?

Using “->” gives me compiler warnings (“Using ‘->’ to access a → or table array”), but seems to work fine, the other spits out lots of runtime errors.

I’ve got a hunch one is accessing the variable contents, the other the addresses – but how do I make the warnings go away?

Thanks a lot, and sorry it it’s been asked. I couldn’t find anything helpful in DM4 nor at Roger Firth’s pages.

syzygy

[otistdog]

The difference is explained somewhat obscurely in the DM4 (bottom of p. 42):

The first alternative is a ‘‘byte array’’, which is identical except that its entries can
only hold numbers in the range 0 to 255, and that it uses the notation → instead of
–>. This is only really useful to economise on memory usage in special circumstances,
usually when the entries are known to be characters, because ZSCII character codes
are all between 0 and 255. The ‘‘Frank Booth’’ array above could safely have been a
byte array.

[zarf (Andrew Plotkin)]

If the array is defined with -> (or “string”), access it with ->. If it’s defined with --> (or “table”), access it with -->.

(The parser breaks these rules for its internal buffer array. Don’t follow its example.)

[syzygy]

Ah, I had completely misread that paragraph…

Thanks for clearing things up for me, now it works fine!

Cheers,

syzygy