LINQ using a where clause to loop through a different array in c#

Question

I would like to return a list of names that do not exist in report. However I am not sure how to loop properly through IEnumerable<string> names using a LINQ. Is there a way to loop through another array using LINQ ?

    private class Report
        {
            public string UserName { get; set; }
            public string city { get; set; }
            public string image { get; set; }
        }


  List<Report>report = await _service(id).ConfigureAwait(false);
  IEnumerable<string> names = await _names(id).ConfigureAwait(false);

// only want to get list of names that do not exist in report

 var newList = reports.Where(x => x.UserName.Where(i => != names)); // doesn't work

I would struct names as a Hashset or Dictionary to prevent O(n^2) — ilkerkaran
– ilkerkaran, Commented Oct 23, 2020 at 16:37

apomene · Accepted Answer · 2020-10-23 16:34:59Z

3

You can use Contains method. Try like:

var newList = reports.Where(x => !names.Contains(x.UserName)));

answered Oct 23, 2020 at 16:34

apomene

14.4k10 gold badges51 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jonesopolis · Accepted Answer · 2020-10-23 16:35:14Z

1

only want to get list of names that do not exist in report

You want to query on names then, to get names back that don't exist.

var newList = names.Where(x => !reports.Any(xx => xx.UserName == x));

answered Oct 23, 2020 at 16:35

Jonesopolis

25.4k12 gold badges72 silver badges115 bronze badges

1 Comment

Chad H Over a year ago

You may also want to add a string.equals(xx, xx.UserName, StringComparison.OrdinalIgnoreCase) check instead of a straight equals

Giopet · Accepted Answer · 2020-11-11 15:16:23Z

0

Try this:

 var newList = names.Where(n => reports.Any(r => r.UserName != n));

answered Nov 11, 2020 at 15:16

Giopet

2514 silver badges5 bronze badges

Collectives™ on Stack Overflow

LINQ using a where clause to loop through a different array in c#

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related