Apple II ?REDIM'D ARRAY ERROR — Array Already Dimensioned

What Does This Error Mean?

?REDIM'D ARRAY in Applesoft means a DIM statement was hit for an array that already existed.
Most often, an array was used implicitly with a default size of 11, and then DIM was called later.
Or DIM is inside a loop that runs more than once.
Either DIM at the very start of the program, or use CLEAR before re-DIM.

Affected Models

Apple II
Apple II Plus
Apple IIe
Apple IIc
Apple IIc Plus
Apple IIGS

Common Causes

Array used (e.g. A(5) = 0) before DIM A(20)
DIM statement inside a FOR/NEXT or GOSUB loop
Two DIM statements for the same name
Array created in subroutine and re-DIMmed in main

How to Fix It

Find the DIM statement.

Note the line number from the error.
LIST that line.
Look earlier in the listing for any reference to the same array name — if you see one before the DIM, that's your bug.
Move all DIM statements to the very top.

Best practice: line 10 (or near it) holds every DIM you'll need.
That way the array exists before any code uses it.
10 DIM A(100), B$(50), C(20,20).
If DIM must run inside a loop: use CLEAR.

CLEAR resets all variables and arrays.
Then DIM is fresh.
But CLEAR also wipes other variables — only use it when you really need the reset.
Check for hidden array references.

Statements like LET A(0) = 1 implicitly DIM A as size 11.
If your DIM A(50) comes later, REDIM'D fires.
Search the listing for every (occurrence — that's where arrays are touched.

Frequently Asked Questions

Why does Applesoft default array size to 11 when not DIM'd?

A bare A(5) = 1 creates A with size 11 (indices 0 through 10).
It saves typing for short arrays but causes REDIM'D errors when you later add DIM.
Always DIM explicitly, even for small arrays — clearer code, no surprises.