Hello, You are changing the “literal array” itself. The #(0 0 0 0) creates an array as part of the compiledMethod and you are changing this. (Yes, many people think that all literals should be immutable…). If you add a #copy it will work. bitArray1 := #(0 0 0 0) copy or create the array at runtime with {0.0.0.0} As for bit array (bit field), I wanted to answer your original question which I will do later… Marcus

On 19 Nov 2015, at 16:12, abdelghani ALIDRA <alidrandco@yahoo.fr> wrote:

Hi everybody,

I am experiencing a very weird behavior with Arrays :

I writed a test case as follows ;

testChange | bitArray1 |

bitArray1 := #(0 0 0 0).

(1 to: bitArray1 size) do: [ :index ||temp| temp := (bitArray1 at: index) + 1. bitArray1 at: index put: (temp). ]. self assert: bitArray1 = #(1 1 1 1)

The thing is that the test succedes the first time but if I run it again it fails. Moreover, if I change the testChange arbitrarily (just add a space and save) the test succeeds the first time then it fails.....etc.

Actually bitArray1 := #(0 0 0 0) changes the value of bitArray1 in the first run but then bitArray1 does not change any more in the next runs.

The problem does not occur if I replace bitArray1 := #(0 0 0 0). with bitArray1 := Array new:4 withAll: 0 .

Any idea where the problem can be? Should I open a bug entry? where?

Abdelghani