Distinct OrderBy in LINQ

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One of my colleagues was curious to know how to implement a Distinct-OrderBy on a custom collection in LINQ. Here’s an example. This example uses the Distinct and OrderBy on the CustomerName property of the Customer class.

C#

class Program
{
    static void Main(string[] args)
    {
        var cust = (from c in Customer.GetCustomers()
          select c.CustName)
          .Distinct()
         .OrderBy(x => x);
        foreach(var cst in cust)
            Console.WriteLine(cst);
        Console.ReadLine();
    }
}

class Customer
{
    public int OrderId { get; set; }
    public string CustName { get; set; }

    public static List<Customer> GetCustomers()
    {
        List<Customer> cust = new List<Customer>();
        cust.Add(new Customer() { OrderId = 1, CustName = "Zack" });
        cust.Add(new Customer() { OrderId = 2, CustName = "Harry" });
        cust.Add(new Customer() { OrderId = 3, CustName = "Jill" });
        cust.Add(new Customer() { OrderId = 4, CustName = "Zack" });
        cust.Add(new Customer() { OrderId = 5, CustName = "Martin" });
        cust.Add(new Customer() { OrderId = 6, CustName = "Jill" });
        return cust;
    }
}

VB.NET

Friend Class Program
    Shared Sub Main(ByVal args() As String)
        Dim cust = (
            From c In Customer.GetCustomers()
            Select c.CustName).Distinct().OrderBy(Function(x) x)
        For Each cst In cust
            Console.WriteLine(cst)
        Next cst
        Console.ReadLine()
    End Sub
End Class

Friend Class Customer
    Public Property OrderId() As Integer
    Public Property CustName() As String

    Public Shared Function GetCustomers() As List(Of Customer)
        Dim cust As New List(Of Customer)()
        cust.Add(New Customer() With {.OrderId = 1, .CustName = "Zack"})
        cust.Add(New Customer() With {.OrderId = 2, .CustName = "Harry"})
        cust.Add(New Customer() With {.OrderId = 3, .CustName = "Jill"})
        cust.Add(New Customer() With {.OrderId = 4, .CustName = "Zack"})
        cust.Add(New Customer() With {.OrderId = 5, .CustName = "Martin"})
        cust.Add(New Customer() With {.OrderId = 6, .CustName = "Jill"})
        Return cust
    End Function
End Class

You can read more about Distinct and OrderBy

OUTPUT

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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.

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