Some Common Operations using List<string> - Part I
I have been writing some articles in the past where I try and demonstrate the capabilities of LINQ using some common examples. Some of these articles are:
In this article and the next one, I will demonstrate some common operations on List<string> using LINQ. I assume that you are familiar with LINQ.
Here are the sample List<string> for demonstration purposes. The VB.NET code has been converted using a conversion tool and accuracy has not been tested.
C#
List<string> lstOne = new List<string>() { "January", "February", "March"};
List<string> lstTwo = new List<string>() { "January", "April", "March"};
List<string> lstThree = new List<string>() { "January", "April", "March", "May" };
List<string> lstFour = new List<string>() { "Jan", "Feb", "Jan", "April", "Feb" };
IEnumerable<string> lstNew = null;
VB.NET
Dim lstOne As New List(Of String) (New String() {"January", "February", "March"})
Dim lstTwo As New List(Of String) (New String() {"January", "April", "March"})
Dim lstThree As New List(Of String) (New String() {"January", "April", "March", "May"})
Dim lstFour As New List(Of String) (New String() {"Jan", "Feb", "Jan", "April", "Feb"})
Dim lstNew As IEnumerable(Of String) = Nothing
We will be printing the results on the console using a simple method shown here:
C#
static void PrintList(IEnumerable<string> str)
{
foreach (var s in str)
Console.WriteLine(s);
Console.WriteLine("-------------");
}
VB.NET
Shared Sub PrintList(ByVal str As IEnumerable(Of String))
For Each s In str
Console.WriteLine(s)
Next s
Console.WriteLine("-------------")
End Sub
Let us get started.
1. Display common elements between two List<string>
C#
// Compare two List<string> and display common elements
lstNew = lstOne.Intersect(lstTwo, StringComparer.OrdinalIgnoreCase);
PrintList(lstNew);
VB.NET
lstNew = lstOne.Intersect(lstTwo, StringComparer.OrdinalIgnoreCase)
PrintList(lstNew)
OUTPUT
2. Display elements found in one List<string> but not in the other
C#
// Compare two List<string> and display items of lstOne not in lstTwo
lstNew = lstOne.Except(lstTwo, StringComparer.OrdinalIgnoreCase);
PrintList(lstNew);
VB.NET
lstNew = lstOne.Except(lstTwo, StringComparer.OrdinalIgnoreCase)
PrintList(lstNew)
Note: The StringComparer.OrdinalIgnoreCase performs a case-insensitive ordinal string comparison
OUTPUT
3. Display distinct elements from a List<string>
C#
// Unique List<string>
lstNew = lstFour.Distinct(StringComparer.OrdinalIgnoreCase);
PrintList(lstNew)
VB.NET
lstNew = lstFour.Distinct(StringComparer.OrdinalIgnoreCase)
PrintList(lstNew)
OUTPUT
4. Convert all elements of a List<string> to UpperCase
C#
// Convert elements of List<string> to Upper Case
lstNew = lstOne.ConvertAll(x => x.ToUpper());
PrintList(lstNew);
VB.NET
lstNew = lstOne.ConvertAll(Function(x) x.ToUpper())
PrintList(lstNew)
OUTPUT
5. Concatenate and Sort two List<string>
C#
// Concatenate and Sort two List<string>
lstNew = lstOne.Concat(lstTwo).OrderBy(s => s);
PrintList(lstNew);
VB.NET
lstNew = lstOne.Concat(lstTwo).OrderBy(Function(s) s)
PrintList(lstNew)
OUTPUT
6. Concatenate Unique Elements of two List<string>
C#
// Concatenate Unique Elements of two List<string>
lstNew = lstOne.Concat(lstTwo).Distinct();
PrintList(lstNew);
VB.NET
lstNew = lstOne.Concat(lstTwo).Distinct()
PrintList(lstNew)
OUTPUT
7. Reverse a List<string>
C#
// Reverse a List<string>
lstOne.Reverse();
PrintList(lstOne);
VB.NET
lstOne.Reverse()
PrintList(lstOne)
OUTPUT
8. Search a List<string> and Remove the Search Item from the List<string>
C#
// Search a List<string> and Remove the Search Item
// from the List<string>
int cnt = lstFour.RemoveAll(x => x.Contains("Feb"));
Console.WriteLine("{0} items removed", cnt);
PrintList(lstFour);
VB.NET
Dim cnt As Integer = lstFour.RemoveAll(Function(x) x.Contains("Feb"))
Console.WriteLine("{0} items removed", cnt)
PrintList(lstFour)
OUTPUT
So these were some common List<string> operations. In the next article[UPDATE: The article is online Some Common Operations using List<string> - Part II], we will see some more advanced operations on the List<string>. Stay tuned! The entire source code of this article can be downloaded over here
I hope you liked this article and I thank you for viewing it.
C# and .NET have been around for a very long time, but their constant growth means there’s always more to learn.
We at DotNetCurry are very excited to announce the The Absolutely Awesome Book on C# and .NET. This is a 500 pages concise technical eBook available in PDF, ePub (iPad), and Mobi (Kindle).
Organized around concepts, this eBook aims to provide a concise, yet solid foundation in C# and .NET, covering C# 6.0, C# 7.0 and .NET Core, with chapters on .NET Standard and the upcoming C# 8.0 too. Use these concepts to deepen your existing knowledge of C# and .NET, to have a solid grasp of the latest in C# and .NET OR to crack your next .NET Interview.
Click here to Purchase this eBook at a Discounted Price!
Was this article worth reading? Share it with fellow developers too. Thanks!
Suprotim Agarwal, MCSD, MCAD, MCDBA, MCSE, is the founder of
DotNetCurry,
DNC Magazine for Developers,
SQLServerCurry and
DevCurry. He has also authored a couple of books
51 Recipes using jQuery with ASP.NET Controls and
The Absolutely Awesome jQuery CookBook.
Suprotim has received the prestigious Microsoft MVP award for ten consecutive times. In a professional capacity, he is the CEO of A2Z Knowledge Visuals Pvt Ltd, a digital group that offers Digital Marketing and Branding services to businesses, both in a start-up and enterprise environment.
Get in touch with him on Twitter @suprotimagarwal or at LinkedIn