Array Question

[atmosphere1212]

Im just wondering if its possible to change the dimension of an array thats already created to 0. I tried redim preserve(0) but the length becomes 1. Also does anyone know how to convert an ArrayList to a 1-dimensional array of some type.

[mutant]

Why would you want to preserve anything in the array that is getting completely emptied? But that aside, you can redim it to -1 if you want to set its capacity to 0.

To convert an Arraylist to an array use its ToArray method.

[mskeel]

Yeah, I just figured this out the other day. VB uses a standard 0 indexed array but when you declare an array you aren't actaully declaring the size but the last index. A collegue's theory is that it's an old throw back from VB6 when arrays where indexed starting at 1. The end result was an array the size you declared it and ending at the index you declared. To illistrate...

 

Dim list(3) as string ==> list.length = 4 (list(0), list(1), list(2), list(3))

 

So redim preserve(0) is saying that you want an array with ending index 0 (length = 1)

[golfnut1969]

...old throw back from VB6 when arrays where indexed starting at 1...

 

VB6 arrays where indexed starting at 0, unless you specified otherwise (eg. list(1 to 3))

[mskeel]

VB6 arrays where indexed starting at 0' date=' unless you specified otherwise (eg. list(1 to 3))[/quote']

Thanks for the clarification. So I guess this phenomenon is just a part of VB.

 

As I said, that was the theory. My original comment still stands...unless someone has a greater insight on why VB doesn't do arrays the way everyone else does.

[Iceplug]

Because of legacy Basic versions. The number representing the array is always the upperbound. While that was fine back then since you could actually do

Dim Myarray(0 To 9) As Integer 'Clearly this is 10 items.

 

In .NET, you cannot define both indices (even if it is just to make yourself know that the bottom bound is always 0).

So, now you can only specify one number (which is the upperbound and not the count).

Dim MyArray(9) As Integer 'Looks like 9 elements but is 10.

 

This is something that needs addressing in some version of VB.NET. At the very least the '0 To' should be back there.

Just a minor annoyance. I've had to get used to it. :)