Convert List(of object) to List(of string)

问题:

Is there a way to convert a List(of Object) to a List(of String) in c# or vb.net without iterating through all the items? (Behind the scenes iteration is fine - I just want concise code)

Update: The best way is probably just to do a new select

myList.Select(function(i) i.ToString()) 

or

myList.Select(i => i.ToString()); 

回答1:

Not possible without iterating to build a new list. You can wrap the list in a container that implements IList.

You can use LINQ to get a lazy evaluated version of IEnumerable from an object list like this:

var stringList = myList.OfType(); 

回答2:

This works for all types.

List

回答3:

If you want more control over how the conversion takes place, you can use ConvertAll:

var stringList = myList.ConvertAll(obj => obj.SomeToStringMethod()); 

回答4:

You mean something like this?

List

回答5:

No - if you want to convert ALL elements of a list, you'll have to touch ALL elements of that list one way or another.

You can specify / write the iteration in different ways (foreach()......, or .ConvertAll() or whatever), but in the end, one way or another, some code is going to iterate over each and every element and convert it.

Marc

回答6:

Can you do the string conversion while the List(of object) is being built? This would be the only way to avoid enumerating the whole list after the List(of object) was created.

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