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David Ten
David Ten

Reputation: 113

ienumerable<string> to list<string>

I have the following code snippet

        string[] lines = objects.Split(new string[] { "\r\n", "\n" }, StringSplitOptions.None);  
        //convert the array into a list for easier comparison
        List<string> StringtoList = lines.OfType<string>().ToList();

        //get the database list here
        List<string> sensitiveApps = testConnection.SelectSensitive();

        //compare the 2 lists to get the difference
        List<string> except = sensitiveApps.Except(StringtoList,StringComparer.OrdinalIgnoreCase);

However, I keep getting the above error, could anyone point me in the right direction?

Upvotes: 0

Views: 2816

Answers (2)

Paul
Paul

Reputation: 3815

While Daniel's suggestion is certainly correct, I'd like to propose an alternative: use HashSet<string> which is better designed for set-based operations like Except.

var set = new HashSet<string>(sensitiveApps, StringComparer.OrdinalIgnoreCase);
set.ExceptWith(lines);

There is no need to do the lines.OfType<string>().ToList() as lines is IEnumerable<string>. Then, if you do need the resulting set as a list, simply call set.ToList().

Hope this helps!

Edit: This assumes that the order of sensitiveApps does not matter.

Upvotes: 1

Daniel Kelley
Daniel Kelley

Reputation: 7737

I'm guessing the last line is throwing an exception. Try changing:

List<string> except = sensitiveApps.Except(StringtoList,StringComparer.OrdinalIgnoreCase);

to:

List<string> except = sensitiveApps.Except(StringtoList,StringComparer.OrdinalIgnoreCase).ToList();

This exception is occurring as Except will be returning an IEnumerable<string>.

Upvotes: 4

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