List Common Elements between two List<string>

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Here’s a simple post that shows how to list common elements between two List<Strings>. Use the Enumerable.Intersect method

C#

class Program
{
    static void Main(string[] args)
    {
        List<string> lstOne =
            new List<string>() { "Jim", "Jack", "Kate", "Nope" };
        List<string> lstTwo =
            new List<string>() { "Jack", "Nope", "Jim" };
        IEnumerable<string> lstNew = null;

        // Compare two List<string> and display common elements
       lstNew = lstOne.Intersect(lstTwo, StringComparer.OrdinalIgnoreCase);
       PrintList(lstNew);

       Console.ReadLine();
    }

    static void PrintList(IEnumerable<string> str)
    {
        foreach (var s in str)
            Console.WriteLine(s);
        Console.WriteLine("-------------");
    }
}

VB.NET

    Sub Main()
        Dim lstOne As New List(Of String)() _
            From {"Jim", "Jack", "Kate", "Nope"}
        Dim lstTwo As New List(Of String)() _
            From {"Jack", "Nope", "Jim"}
        Dim lstNew As IEnumerable(Of String) = Nothing

        ' Compare two List<string> and display common elements
        lstNew = lstOne.Intersect(lstTwo, StringComparer.OrdinalIgnoreCase)
        PrintList(lstNew)

        Console.ReadLine()
    End Sub

    Private Sub PrintList(ByVal str As IEnumerable(Of String))
        For Each s In str
            Console.WriteLine(s)
        Next s
        Console.WriteLine("-------------")
    End Sub

OUTPUT

Read some more tips in my article over here Some Common Operations using List<string>

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About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.