CODEWITHSUNDEEP
c#linq
user12241407
user12241407

Reputation:

Compare two lists and remove items that are not found in list2

I have two lists-

List<String> List1;
List<File> List2;

The contents are as follows-

List1                   List2
-----                   -----
String                  ID    FileName     LastWrite

tttaaaajk34j34          1       aaa        01-02-2019
oooccc                  2       bbb        14-09-2018
ddd                     3       ccc        23-06-2019
ttt                     4       ddd        15-10-2016
aaa2832kajj             5       eee        20-08-2012

I want to compare List1 with List2 and remove items from List2 that are found in the List1.

Result-

List2
----
ID     FileName

2       bbb
4       ddd
5       eee

My Code-

List1.Where(f => !List1.Any(str => str.FileName.Contains(List2)))

The Problem-

This doesn't work. It throws below exception as List2 is a List, unlike List1 which is List.

'String does not contain a definition for filename and no extension method filename accepting a first argument of type string..

Upvotes: 0

Views: 1904

Answers (1)

RoadRunner
RoadRunner

Reputation: 26315

You could just filter out the files using LINQ:

List1.Where(f => !List2.Any(str => str.Contains(f.FileName)))

Explanation:

  • Use Enumerable.Where() to first filter out the files from List1, you want to keep.
  • Use String.Contains() to check if Enumerable.Any() of the files from List2 have substring filenames FileName from List1. In this case we make sure to use ! operator in the predicate to ensure we don't keep files that have been found in List2.

UPDATE

As per updated requirements in the question just switch around List1 and List2. Your new query should be:

List2.Where(f => !List1.Any(str => str.Contains(f.FileName)))

Upvotes: 6

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