Dynamic arrays

[Dusty]

How can I make my dynamic array ? I'm curios how the
ArrayList does it.
For example:
string[] s = new string[16];

and later I want to expand this array to more than 16
elements without loosing previous data (like ReDim in
VB).

Any ideas ?

[Mattias Sjögren]

Any ideas ?

Allocate a new, larger array, copy over the existing elements, and
drop the reference to the old array. That's what ReDim does, and I'm
guessing that the ArrayList does something similar.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.

[Val Savvateev]

If you look at an ArrayList instaince in the debugger's Watch window you'll
descover that it has an internal (private?) member called _items and it's
just an array of Objects. So I would imagine Mattias' guess is correct -
ArrayList allocates/reallocates regular arrays behind the scenes, however
that process may be optimized in a way...

Val.

"Dusty" <du***@ptt.yu > wrote in message
news:%2******** ********@tk2msf tngp13.phx.gbl. ..

How can I make my dynamic array ? I'm curios how the
ArrayList does it.
For example:
string[] s = new string[16];

and later I want to expand this array to more than 16
elements without loosing previous data (like ReDim in
VB).

Any ideas ?

[Uriel Julio [MSFT]]

Hello,

ArrayList is a dynamic array. You should add elements to it by using its
Add method. There are two properties that you can check to get its size:
.Count and .Capacity. The capacity will always be equal to or higher than
the count. You could think of it as similar to a vector class. If you want
to trim it so that the capacity is the count, you can call its TrimToSize()
method.

I hope that helped.

--------------------

From: Mattias Sjögren <ma************ ********@mvps.o rg>
Subject: Re: Dynamic arrays
Date: Wed, 30 Jul 2003 01:31:02 +0200
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Any ideas ?

Allocate a new, larger array, copy over the existing elements, and
drop the reference to the old array. That's what ReDim does, and I'm
guessing that the ArrayList does something similar.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.

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