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

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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>

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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.