Concatenate Unique Elements of two List<String> and Sort using LINQ

Here’s how to concatenate unique elements of two List<String> and then Sort them using LINQ. Use the Enumerable.Concat method

C#

static void Main(string[] args)
{
List<string> lstOne = 
new List<string>() { "Jack", "Henry", "Amy" };
List<string> lstTwo = 
new List<string>() { "Hill", "Amy", "Anna" };
IEnumerable<string> lstNew = null;
// Concatenate Unique Elements of two List<string>
lstNew = lstOne.Concat(lstTwo).Distinct().OrderBy(x => x);
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 {"Jack", "Henry", "Amy"}
Dim lstTwo As New List(Of String)() From {"Hill", "Amy", "Anna"}
Dim lstNew As IEnumerable(Of String) = Nothing
' Concatenate Unique Elements of two List<string>
lstNew = lstOne.Concat(lstTwo).Distinct().OrderBy(Function(x) x)
PrintList(lstNew)
Console.ReadLine()
End Sub

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

OUTPUT



As you can see, Amy is not repeated twice as we called the IEnumerable.Distinct of the concatenated list.

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