Collection indexes

[songie D]

If you remove an item from a collection (that is derived from CollectionBase and thus implements IList
will the index property automatically 'shuffle' up one
i.e. if of {0, 1, 2, 3} I delete item 2, then will I be left with {0, 1, 2} or {0, 1, 3}
Basically I am implementing a custom collection and wondered if I could rely o
the fact that for(int i=0; i<List.Count; i++) would always be an appropriate loop.

[Ravikanth[MVP]]

Hi

The index will be updated dynamically.

--
Ravikanth[MVP]

"songie D" wrote:

If you remove an item from a collection (that is derived from CollectionBase and thus implements IList)
will the index property automatically 'shuffle' up one?
i.e. if of {0, 1, 2, 3} I delete item 2, then will I be left with {0, 1, 2} or {0, 1, 3} ?
Basically I am implementing a custom collection and wondered if I could rely on
the fact that for(int i=0; i<List.Count; i++) would always be an appropriate loop.

[Stoitcho Goutsev \(100\) [C# MVP]]

Hi songie,

If you call Remove or RemoveAt method you remove the element of the
collection, thus all the elements on the right side of the removed one shift
left 1 position (left or right ofcourse is completely subjective)

Anyway the indexes always are 0,1,2,....,Count - 1 without gaps in-between.

If you want to keep the count (assuming that you have collection of
references ) you can do

myList[k] = null; in this case you don't remove anything an no shifting
occurs.

However
for(int i=0; i<List.Count; i++) almost never works with removing elements
because anytime you remove an element you skip one (if you don't do
correction of 'i' ofcourse).

But if you do

for(int i = List.Count - 1; i >=0 ;i--)

this will work in all the cases as far as removing is concerned.

--
HTH
Stoitcho Goutsev (100) [C# MVP]
"songie D" <an*******@discussions.microsoft.com> wrote in message
news:EF**********************************@microsof t.com...

If you remove an item from a collection (that is derived from CollectionBase and thus implements IList) will the index property automatically 'shuffle' up one?
i.e. if of {0, 1, 2, 3} I delete item 2, then will I be left with {0, 1, 2} or {0, 1, 3} ? Basically I am implementing a custom collection and wondered if I could rely on the fact that for(int i=0; i<List.Count; i++) would always be an

appropriate loop.

[songie D]

Thanks, that's what I wanted to know.
I'm probably going to be doing removing by object.
This is only for the purposes of the enumerator.

"Stoitcho Goutsev (100) [C# MVP]" <10*@100.com> wrote in message
news:%2****************@TK2MSFTNGP11.phx.gbl...

Hi songie,

If you call Remove or RemoveAt method you remove the element of the
collection, thus all the elements on the right side of the removed one shift left 1 position (left or right ofcourse is completely subjective)

Anyway the indexes always are 0,1,2,....,Count - 1 without gaps in-between.
If you want to keep the count (assuming that you have collection of
references ) you can do

myList[k] = null; in this case you don't remove anything an no shifting
occurs.

However
for(int i=0; i<List.Count; i++) almost never works with removing elements
because anytime you remove an element you skip one (if you don't do
correction of 'i' ofcourse).

But if you do

for(int i = List.Count - 1; i >=0 ;i--)

this will work in all the cases as far as removing is concerned.

--
HTH
Stoitcho Goutsev (100) [C# MVP]
"songie D" <an*******@discussions.microsoft.com> wrote in message
news:EF**********************************@microsof t.com...

If you remove an item from a collection (that is derived from

CollectionBase and thus implements IList)

will the index property automatically 'shuffle' up one?
i.e. if of {0, 1, 2, 3} I delete item 2, then will I be left with {0, 1,

2} or {0, 1, 3} ?

Basically I am implementing a custom collection and wondered if I could

rely on

the fact that for(int i=0; i<List.Count; i++) would always be an

appropriate loop.