How to remove an item while iterating over collection?

I would like to use the AS "for each" syntax to loop over a collection of items. Within the loop I sometimes need to remove an item from the collection I am iterating over.

Using a "for" loop, I would code thi开发者_运维技巧s like (note the "--" operator to move the index back):

for (var n:int=0; n<ac.length; n++) {
    var s:String = ac.getItemAt(n) as String;
    if (s == 'c')
        ac.removeItemAt(n--);
}

Is it also possible to do something similar using a "for each" construct?

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In all of the languages I know of, the foreach requires that the collection it iterates through does not change while iterating.

So, the simple answer would be - no, you can't. But the way you're doing it in your sample is OK.

edit: What you could do is to create a new list of items that need to be deleted inside a foreach(of itemList), and than go through another foreach(of deletedItems) and remove from itemList. The only thing is to worry about is that you don't iterate over the collection you're changing.

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Copy your arraycollection or your data structure. Do a reverse for loop on your original and remove the elements at the required index from the copied structure.

Output: Your new data structure minus the elements you dont want to keep.

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It is possible if the for each construct you are talking about allows access to an index during the iteration but even then it is sure to backfire because I am certain most languages assume the collection is not suddenly going to change its "length" or its indices during the iteration if you are using for each. If you put in a index parameter then you are back to a regular for construct so the whole exercise ends up being futile.

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This is possible with the for ... in loop. The iteration is not disrupted.

var o:Object = { a: 0, b: 1, c:2 };
for (var k:String in o)
{
   delete o[k];
}