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C# Extract list of fields from list of class

Tags:

c#

linq

I've got a list of elements of a certain class. This class contains a field.

class Foo {public int i;}
List<Foo> list;

I'd like to extract the field from all items in the list into a new list.

List<int> result = list.ExtractField (e => e.i); // imaginary

There are surely multiple ways to do that, but I did not find a nice-looking solution yet. I figured linq might help, but I was not sure how exactly.

like image 583
mafu Avatar asked Jun 15 '09 07:06

mafu


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1 Answers

Just:

List<int> result = list.Select(e => e.i).ToList();

or

List<int> result = list.ConvertAll(e => e.i);

The latter is more efficient (because it knows the final size to start with), but will only work for lists and arrays rather than any arbitrary sequence.

like image 147
Jon Skeet Avatar answered Oct 06 '22 16:10

Jon Skeet