Re: How do you modify an array while iterating through it?
From: Gustaf Liljegren (gustaf.liljegren_at_bredband.net)
Date: 02/17/04
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Date: Tue, 17 Feb 2004 16:15:10 +0100
"Jon Skeet [C# MVP]" <skeet@pobox.com> wrote:
> You can't change a list while you're iterating through it. One common
> solution is to build up another list containing the items you *want* to
> add to the list, and then add all of them after you've finished
> iterating. (You could use ArrayList.AddRange for that.)
Thanks for all your help. I see that I have not given a good enough
description. It's a grouping problem. The input data is a list of accounts
(identified by name) where some accounts occurs more than once. I want the
accounts grouped so that the amounts are summed up. For example, this input
data
Account 1: 2.50
Account 2: 7.00
Account 1: 1.50
Account 3: 9.00
Account 2: 3.50
Account 2: 6.00
Account 3: 3.50
Account 1: 6.50
shall result in these groups (each in an Account object):
Account 1: 10.5
Account 2: 16.5
Account 3: 12.5
My way of doing this is looping through the input data, account by account.
If the account has already been found, I just add the amount from the
current account object. If not, I add the whole object to the array. But it
won't work, since I can't add items to the array while iterating through it.
Maybe I need an Accounts collection class with methods like AccountExists(),
AddAccount() and UpdateAmount().
Gustaf
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