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How to delete item in list while iterating through the list?

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Posted on by huangyvonne

Hi in X++, is it possible to delete items while iterating through list and not causing error? I know it's doable in C# but not sure how x++ language handle it.

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ergun sahin 8,826 Moderator on at

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at the moment, I can't look for 365 but at 2012 for iterating a list you can use listIterator or listEmulator. ListIterator has delete method but emulator dont have such a method. In 2012 I don't use iterator (server/client side pointer problem) but I don't think 365 have this problem

https://docs.microsoft.com/en-us/dotnet/api/microsoft.dynamics.ax.xpp.listiterator

www.google.com/.../

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Hossein.K 6,648 on at

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Hi,

To remove objects from a list you need to use an iterator.

In X iterators require the developer to write a loop with calls to more() and next() to check if there are any elements left and make iterator advance to the next element.

list = new List(Types::String); list.addEnd('a'); list.addEnd('b'); list.addEnd('c'); list.addEnd('d'); iter = new ListIterator(list); while (iter.more()) { value = iter.value(); if (true) // check value { iter.delete(); } else { iter.next(); } } info(list.toString());

Either do a delete() or a next(). Not both. The same goes for maps and sets.

And by the way, if you want to do anything other than delete elements it’s highly recommended you use enumerators instead of iterators.

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Martin Dráb 237,801 Most Valuable Professional on at

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You can also consider alternative designs. For example, you can have a Set with all items and add items to be deleted to another Set. Then you'll use Set::difference() to create a set without deleted items:

Set remainingItems = Set::difference(allItems, deletedItems);

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huijij 19,811 on at

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Hi Yvonne,

As the upstairs insight,Here is a link about the Iterator for deleting item in list:

Enumerator and Iterator

regards

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