Question on Arrays (beginner)

[jgq85]

Hi I have a question regarding arrays as I'm still trying to grasp the concept.

Over at http://www.autoitscript.com/wiki/Arrays, it states you have to do a -1 to get the actual index (since computer counts starting at 0)

So its example:

Local $arr[3] = ["element 1", "element 2", "element 3"]
 
For $i = 0 to 3 - 1 ; We have an array with three elements but the last index is two.
ConsoleWrite($arr[$i] & @LF)
Next

My question is, why wouldn't you just change "For $i = 0 to 3 -1" to "For $i = 0 to 2"?

 

 

[somdcomputerguy]

My question is, why wouldn't you just change "For $i = 0 to 3 -1" to "For $i = 0 to 2"?

 

Well you could if you wanted. With larger arrays though, it's easier to use UBound -1, or just UBound if that's the case.

Edited July 19, 2014 by somdcomputerguy

[Melba23]

jgq85,

If you already know the size of the array, then of course you can use the actual value for the top index:

Local $arr[3] = ["element 1", "element 2", "element 3"]
For $i = 0 to 2                                            ; You can use the actual value here
    ConsoleWrite($arr[$i] & @LF)
Next

But if you have an array of unknown size (after using FileReadToArray for example) you need to do as somdcomputerguy suggested - use UBound and subtract 1 to get the top index:

Local $aLines = FileReadToArray("File_Path")
For $i = 0 to UBound($aLines) - 1                          ; But here you need to calculate the top index
    ConsoleWrite($arr[$i] & @LF)
Next

Just so you know, in the new Beta you get the number of lines read returned in @extended so you could use that instead.

M23