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Assigning variables to an array


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I can do

   Global array[2] = ["one", "two"]

or I can do

   Global array[2]

   array[0] = "one"

   array[1] = "two"

But I can not do

   Global array[2]

   array = ["one", "two"]

Why does this not work? Is there any way (i.e. setting) that will make it work?

 

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Hi @PapaOz,

yes this is the case. Syntax error for the last variant:

#include-once
#include <Array.au3>

Global $aTest1[2] = ["one", "two"]
_ArrayDisplay($aTest1) ; works

Global $aTest2[2]
$aTest2[0] = "one"
$aTest2[1] = "two"
_ArrayDisplay($aTest2) ; works

Global $aTest3[] = _
    [ _
        'one', _
        'two' _
    ]
_ArrayDisplay($aTest3) ; works

; syntax error:
; Global $aTest4[2] = ["one", "two"]
; $aTest4 = ["one", "two"]
; _ArrayDisplay($aTest4)

But why do you need this exactly this syntax? It's not AutoIt valid. The other three variants are fine so I don't see the problem to be honest!?

Best regards
Sven

Edited by SOLVE-SMART

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Thank you. @SOLVE-SMART for responding to my post.

I don't "need" the exact syntax I asked about.  I agree that the multi-line solutions work.  I was just curious why a syntax that works in a declaration doesn't also work in an assignment.

I have to declare my array as Global before I can use it, but at the time I declare it I do not know how many elements it will need to hold so I give it [0].  

Later, within a function, I ReDim the array and populate it with several variables.  If I do that with individual assignments to each element it results in a lot of lines in the script.  I would prefer to be able to make the assignments in a single statement.  It's a personal style issue. 


Thank you, @abolutionist for reminding me that a function can return an array.  I think that will be satisfactory and I will mark it as a solution.  

I am at best an "advanced beginner" with AutoIt so I am grateful for these forums.  They usually have answers to my questions that search engines can find.  I couldn't find anything like the responses I got to this thread with Google, so I posted here.  Thank you both for your help.

 

 

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6 hours ago, PapaOz said:

I have to declare my array as Global before I can use it, but at the time I declare it I do not know how many elements it will need to hold so I give it [0].  

Later, within a function, I ReDim the array and populate it with several variables.  If I do that with individual assignments to each element it results in a lot of lines in the script.  I would prefer to be able to make the assignments in a single statement.  It's a personal style issue. 

@PapaOz Are you aware that even though you declared your array as Global at the beginning of the script, you can still re-declare it as Global again (even if inside a function) when you want to populate it later if you intend to completely replace the array contents with your new contents? You only need to ReDim the array if you want to keep the existing contents and add to it. Using the Global keyword lets you do all of your assignments in a single statement as you said you wanted to. It even resizes the array if needed since it's  really just replacing the Global array you initially declared.

#include <Array.au3>

Global $aArray[2] ; declare a global array with 2 elements
SomeFunction()
_ArrayDisplay($aArray)

Func SomeFunction()
    Global $aArray = ["One", "Two", "Three", "Four"] ; populate the global array with 4 elements
EndFunc

 

Edited by TimRude
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Hi @TimRude,

I agree with you that this is a theoretical valid approach, but it's also "code smell" because the declaration of a global scoped variable (array) within a function isn't okay (is wrong). You could do it in this way, yes, but since there are four other ways to handle this, please do not suggest it. Anyways, thanks for different mind approach 👍 .

Best regards
Sven

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@SOLVE-SMART Respectfully, I don't see a problem with redeclaring a global array inside a function, especially if the array was originally declared as Global already in the main code section. Global is global. The whole point of a global variable or array is to allow it to be read/set from anywhere in the code. In this case all you're doing by reusing the Global keyword is conforming to the syntax requirements in order to assign values to an already global array. I know some programming languages may not allow declaring a global variable inside a function and that's their prerogative. But if AutoIt is flexible enough to handle it, so am I.

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Don't ReDim, don't redeclare, and don't return an entire array (needlessly moving data back and forth); just parse ByRef:

#include <Array.au3>

Local $aArrayTarget[5] = ["0", "1", "2", "3", "4"]

_AddLocallyDefinedArray($aArrayTarget)
_ArrayDisplay($aArrayTarget, "Target and Source concatenated")

Func _AddLocallyDefinedArray(ByRef $aTarget)
    If Not (IsArray($aTarget) and UBound($aTarget,0)=1) Then Return
    Local $aArraySource[5] = ["5", "6", "7", "8", "9"]
    _ArrayConcatenate($aTarget, $aArraySource)
EndFunc

This way it'll work regardless of whether the target is global.

Edited by RTFC
sloppy copy
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9 hours ago, TimRude said:

@SOLVE-SMART Respectfully, I don't see a problem with redeclaring a global array inside a function, especially if the array was originally declared as Global already in the main code section. Global is global. The whole point of a global variable or array is to allow it to be read/set from anywhere in the code. In this case all you're doing by reusing the Global keyword is conforming to the syntax requirements in order to assign values to an already global array. I know some programming languages may not allow declaring a global variable inside a function and that's their prerogative. But if AutoIt is flexible enough to handle it, so am I.

Fair enough @TimRude. Thanks for your statement 👍 . I didn't want to forbid you to do this, but I also would not suggest this way/approach. I guess and hope @PapaOz already have a feeling about the "why" and how to handle such situations in AutoIt through the posts here 😀

Best regards
Sven

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On 1/21/2023 at 8:42 AM, PapaOz said:

I don't "need" the exact syntax I asked about.  I agree that the multi-line solutions work.  I was just curious why a syntax that works in a declaration doesn't also work in an assignment.

Basically, you can use that syntax when you create the array because you're defining its size/scope that that point. The ['value','value2'] syntax is a sequential assignment of values, but it (to me) doesn't make much sense to use that syntax after the array is created/modified. Say you made $aArray[10], and you wanted to update indexes 6,7,8, what would that look like? [Default,Default,Default,Default,Default,Default,'updated6','updated7','updated8']? That seems like to me it's a good reason why it's not supported after declaration. It's probably only supported during declaration because of a feature request. Here's an example of a post from 2005 where that syntax wasn't yet supported.

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