can't resize an array using the Execute function

[jhonford1]

for some reason i cant use redim inside execute and i also can't assign values to the array using it any ideas?

example:

#include <array.au3>
Global $test[3] = [1,2,3]
_ArrayDisplay($test)
Execute("ReDim $test[0]")
_ArrayDisplay($test)

expected outcome: an array of [0] size

also 

Execute("$test[0] = 5")

doesn't seem to do anything

[BrewManNH]

Why in the world are you using Execute?

[jdelaney]

You can't redim any array to [0]...what you want is to just set the value of the variable = "" (maybe?).  If not, then what you are trying to do is not clear.

Edited April 3, 2018 by jdelaney

[jchd]

4 minutes ago, jdelaney said:

You can't redim any array to [0]

Yes you can!

[spudw2k]

5 minutes ago, jdelaney said:

You can't redim any array to [0]

Technically you can ReDim to [0]...I'm just not sure the usefulness or application where you would need to do this.

 

2 hours ago, BrewManNH said:

Why in the world are you using Execute?

I am also curious.  

[jdelaney]

Huh, was that always the case?  Interesting.

Well, you definitely can't assign value to an array with ubound=0. (prove me wrong with some 'new' way)

Edited April 3, 2018 by jdelaney

[jchd]

It's plain obvious you can't store anything in an array having been declared as containing zero row and this is exactly why they're useful!

Despite being unable to store anything empty arrays have their use:

• You don't have to declare an array with an inexact number of rows (or first dimension) in numerous cases where you're going to accumulate results there, w/o having the faintest idea how many you'll have to store, if any. This allows to satisfy a useful invariant of the function, saying that both $aResult and UBound($aResult) always match what has been processed so far.
• A function returning an array can do so in any case where there is no result, conforming to a more simple specification. Many functions created before empty arrays were available used to return an error in such case; this is technically wrong.
• I believe (without being definitely positive) that COM objects may accept and/or return Nul arrays, which easily translates into AutoIt empty array. If memory serves at my age, it's for that or similar reason that empty arrays were introduced.
• Empty arrays are consistent at first-order with OO containers (lists, bags, queues, arrays, fifos, sets, whatever): when you create an instance of such a beast it's initially empty.

An error should only ever mean that the function hit an abnormal condition where it can't perform it's intended job. It generally isn't abnormal to find no match for a search. Easy idealized example:

_FileListToArray("没有这样的目录")           ; is likely to return an error 1 (text means "No such directory")
_FileListToArray(".", "没有这样的文件")      ; shouldn't return an error but an empty array (text means "No such file")

Of course this example is bad, since the function is currently specified to return an array with the number of entries in row 0 (another design error in  my view, but too late to fix).

 

Changelog says:

3.3.10.0 (23rd December, 2013) (Release)

• Added: Empty arrays.

[jhonford1]

First thank you everyone for your replys

now let me answer some of the question:

Q:why do i need to resize them?

A:basicly becasue i want to empty them (this is the task that was given to my by the original writer of the script)

Q:why in the world do i have to use execute?

A:becasue the names of the arrays that i need to empty come for another array(again im not the writer of the code). using execute was just an attempt if you have a better idea the sure i will delete my line

Global $arraynames = ["$array1", "$array2", "$array3"]
for $i= 0 to UBound($arraynames)-1
    execute("ReDim" & " " & $arraynemaes[$i] & "[0]")
Next

i was thinking of using something like this to empty all of the arrays but it does'nt work

note: i'm NOT allowed to change the original code in any way  therefore i have to find a way using what i have and i can't post the script as well :/

also now im really curious why the the execute function failed in my attaempt

[Subz]

Probably not the best method but you could do something like:

#include <Array.au3>
Global $aArray1[4] = [3,1,2,3]
Global $aArray2[4] = [3,1,2,3]
Global $aArray3[4] = [3,1,2,3]
_ArrayDisplay($aArray1, "Before")
_ArrayDisplay($aArray2, "Before")
_ArrayDisplay($aArray3, "Before")
Global $aArrayNames = ["$aArray1", "$aArray2", "$aArray3"]
For $i = 0 to UBound($aArrayNames)-1
    For $j = UBound(Execute($aArrayNames[$i])) - 1 To 0 Step - 1
        Execute("_ArrayDelete(" & $aArrayNames[$i] & ", " & $j & ")")
    Next
Next
_ArrayDisplay($aArray1, "After")
_ArrayDisplay($aArray2, "After")
_ArrayDisplay($aArray3, "After")

 

[jhonford1]

13 minutes ago, Subz said:

Probably not the best method but you could do something like:

#include <Array.au3>
Global $aArray1[4] = [3,1,2,3]
Global $aArray2[4] = [3,1,2,3]
Global $aArray3[4] = [3,1,2,3]
_ArrayDisplay($aArray1, "Before")
_ArrayDisplay($aArray2, "Before")
_ArrayDisplay($aArray3, "Before")
Global $aArrayNames = ["$aArray1", "$aArray2", "$aArray3"]
For $i = 0 to UBound($aArrayNames)-1
    For $j = UBound(Execute($aArrayNames[$i])) - 1 To 0 Step - 1
        Execute("_ArrayDelete(" & $aArrayNames[$i] & ", " & $j & ")")
    Next
Next
_ArrayDisplay($aArray1, "After")
_ArrayDisplay($aArray2, "After")
_ArrayDisplay($aArray3, "After")

 

I was thinking of something similar tbh, but i still dont understand why my method failed :/

[BrewManNH]

Are you trying to empty the arrays, or delete them? Because you can use $array = "" to empty an array and turn it into a simple variable.

[Jos]

15 hours ago, BrewManNH said:

Why in the world are you using Execute?

Did we get an answer on this pretty basic question as I have no clue why it is used in all those scripts posted yet?

Jos

[jhonford1]

1 hour ago, BrewManNH said:

Are you trying to empty the arrays, or delete them? Because you can use $array = "" to empty an array and turn it into a simple variable.

I know that i can do that how ever how do you use it multiple arrays? (The script will decide which arrays to delete at run time i can't write it manually )

 

18 minutes ago, Jos said:

Did we get an answer on this pretty basic question as I have no clue why it is used in all those scripts posted yet?

Jos

Yes, i've already answered this question 

 

8 hours ago, jhonford1 said:

Q:why in the world do i have to use execute?

A:becasue the names of the arrays that i need to empty come for another array(again im not the writer of the code). using execute was just an attempt if you have a better idea the sure i will delete my line

 

[BrewManNH]

You can't use Execute to declare or redeclare a variable.

another question that comes to mind, WHY do you need to delete these arrays? What's wrong with just leaving them there?

8 hours ago, jhonford1 said:

note: i'm NOT allowed to change the original code in any way  therefore i have to find a way using what i have and i can't post the script as well

Then isn't all of this a moot point anyways? You're trying to change the code, but you're not allowed to change the code? That's a very confusing issue you have there.

[jhonford1]

 

47 minutes ago, BrewManNH said:

Then isn't all of this a moot point anyways? You're trying to change the code, but you're not allowed to change the code? That's a very confusing issue you have there.

i need to write a piece of code that work with the existing script without modifying it (just adding my piece to the script)

[Jos]

Why? I would prefer doing it the right way in stead of mickey mousing around ... no?

Jos

[BrewManNH]

1 hour ago, jhonford1 said:

i need to write a piece of code that work with the existing script without modifying it (just adding my piece to the script)

Whoever wrote the original script (that you can't modify for some reason) needs to rewrite his/her part of it and make it work better, trying to code around someone else's ineptitude is bound to be frustrating.