List Common Elements between two List<string>

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, ASP.NET Architecture MVP works as an Architect Consultant and provides consultancy on how to design and develop Web applications.

Suprotim is also the founder and primary contributor to DevCurry, DotNetCurry and SQLServerCurry. He has also written an EBook 51 Recipes using jQuery with ASP.NET Controls.

Follow him on twitter @suprotimagarwal