ReDim and Array Dimension syntax

[donnyh13]

Good day AutoIt Community;

I have a question regarding changing an Array’s dimension, using ReDim. I have come across a curiosity, and wondered “why”? Perhaps it is some common knowledge thing I have missed?

The question is: Why can I not ReDim an Array from a 2D array to a 1D array and use corresponding syntax? i.e:

Local $aTest[1][2]


ReDim $aTest[1][1]


$aTest[0] = 10 ; Fails -- Array variable has incorrect number of subscripts or subscript dimension range exceeded.


$aTest[0][0] = 10 ; Works

 I am trying to make a function where the user has the option to add a column, if they decide not to, the resulting array would be a single column. Thus the dimension would be a variable instead of a integer, as the above example is. Is my method the only problem? And instead to make a single column I need to do it like this:

ReDim $aTest[1]

Thanks for any clarification.

 

[Andreik]

It has nothing to do with ReDim, it fails because you have a multidimensional array so when you assign a value you must specify the dimensions. If I understand well what you need, you can have a 1D array and the value assigned for each index should be a simple value or an array based on the option selected by the user. Something like that.

Local $aTest[10]

Local $Options[2]

$aTest[0] = 0
$aTest[1] = $Options
...

[genius257]

Hi @donnyh13

Array sizes are fixed to the number of dimensions you need between 1 and 64.

Each dimension in the array is represented via one pair of square brackets.

; One dimension
Global $a[1]
;Two dimensions
Global $a[1][1]
;Three dimensions
Global $a[1][1][1]

So your current ReDim expression changes the size the the size of that dimension, but not the number of dimensions.

34 minutes ago, donnyh13 said:

And instead to make a single column I need to do it like this:

ReDim $aTest[1]

Yes that would reduce your 2D array to a 1D array.

 

I am not entirely sure i understand what your function should do, but if you only need to add a column to the array, maybe something like this:

#include <Array.au3>

Global $aTest[1][2]
$aTest[0][0] = 10
$aTest[0][1] = 20

_ArrayDisplay($aTest)
MyFunction($aTest, 25, True)
_ArrayDisplay($aTest)
MyFunction($aTest, 30, False)
_ArrayDisplay($aTest)

Func MyFunction(ByRef $array, $value, $addColumn = False)
    If $addColumn Then Redim $array[1][UBound($array, 2) + 1]
    $array[0][UBound($array, 2) - 1] = $value
EndFunc

 

[donnyh13]

  

Alright, thanks guys. The problem clearly stems from my lack of an understanding of dimensional arrays. I was previously understanding that $aArray[1][2] meant 1 row 2 columns/dimensions; and thus $aArray[1][1] would mean 1 column/dimension. But I now see dimensions is not the same as columns 😳.  Which should have been obvious, had I read the help file slowly.

Thank you for the examples, and help. As for my goal, what I am working with is obtaining Objects for Shapes contained in a LibreOffice document. Currently column 0 contains the object, and then optionally the other columns can contains an integer corresponding to some constants, and also the implementation name, helping to identify what shape the Object is for, and so on for each row. Thus if the user only wants the Objects, it would only a 1D array of Objects. I was attempting to limit the number of If/Else's. But I think I have a better grasp of how to solve it now.

[Andreik]

If your multidimensional array have two dimensions then you can still think at the array in terms of rows and columns but it's good to know that dimensions are not the same thing as rows and columns.

[donnyh13]

Okay, thanks for that clarification @Andreik