How to assign to an array in Pascal?

Question

I'm getting an error I don't understand. I am trying to just assign a value to an element of an array in pascal.

function TestingThing() : Integer;
type
  IntegerArray  = array[0..$effffff] of Integer;
  PIntegerArray = ^IntegerArray;
var
  I: Integer;
  D: PIntegerArray;
begin
  for I := 0 to 5 do
    D[ I ] := I;
end;

This gives me an error on the line

D[I] := I

Error: Incompatible types: got "LongInt" expected "IntegerArray"

D is pointer, so you need to dereference it D^[ I ] := I; — Iłya Bursov
– Iłya Bursov, Commented Dec 13, 2023 at 20:00
@DelphiCoder Because array[0..$effffff] is a bogus data type. @Anthony does not want to allocate space for and use 251658239 integers, but only six. — Kai Burghardt
– Kai Burghardt, Commented Dec 31, 2023 at 0:46
@KaiBurghardt your comment doesn't make any sense. How are you supposed to know that? — DelphiCoder
– DelphiCoder, Commented Dec 31, 2023 at 8:01

Remy Lebeau · Accepted Answer · 2023-12-13 20:33:07Z

4

D is a pointer to an array of integers, it is not a pointer to a single integer, like you are expecting.

So, when you do D[I], you are indexing into D and the resulting element is an array, and you can't assign a value to an array, hence the error.

You need to either:

dereference D before you index into the array it points at:

D^[ I ] := I;
or, you need to change D to be a PInteger that points at the 1st Integer in the array, and then D[I] will work as expected.

answered Dec 13, 2023 at 20:33

Remy Lebeau

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1 Comment

fpiette Over a year ago

And D must be initialized to point to some memory for the array.

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