Left Function for Strings in VB.Net

Question

User2023521679 posted

Since the string class does not have a Left method, how would you do this in VB.Net. I could use String.SubString(0, x),  but the problem with this method is that it throws an exception if the String is not at least x characters long.

Should I use the Microsoft.VisualBasic.Left function instead? 

Answer 1

User560403387 posted

Just use what works. If the Microsoft.VisualBasic.Strings.Left does what you need, use it. If you want a prettier solution, add a 'Left' extension method to the string class.

Menno

Answer 2

User-1360095595 posted

I would validate the length of the string, and then use Substring(). 

Answer 3

User-1199946673 posted

Should I use the Microsoft.VisualBasic.Left function instead? 

 

You could also create your own Left (extension) method:

    <System.Runtime.CompilerServices.Extension()> _
    Public Function Left(ByVal [string] As String, ByVal length As Integer) As String
        If length < [string].Length Then length = [string].Length
        Return [string].Substring(0, length)
    End Function

 

Answer 4

User-952121411 posted

Should I use the Microsoft.VisualBasic.Left function instead? 

 

There is nothing wrong or incorrect about using the Microsoft.VisualBasic namespace methods in VB.NET.  In fact even some C# developers, import that namespace and use those functions in their programming too!  I typically try to use the purely .NET namespaces instead of the VB ones, but sometimes if I need to write code quickly, I go back to using the old trusty methods like Right(), Left(), Mid(), etc.

Answer 5

User2023521679 posted

 Thanks. I new I could use them, I just wasn't sure if the use of these functions were deprecated under .Net.

I'm surprised that String.Left(...) and String.Right(...) weren't included in the string classes methods.

Answer 6

User-1996290357 posted

Hi hans_v

Just a quick correction to your comparation operator, and the opposite RIGHT function:

<System.Runtime.CompilerServices.Extension()> _
Public Function Left(ByVal [string] As String, ByVal length As Integer) As String
    If length > [string].Length Then length = [string].Length
    Return [string].Substring(0, length)
End Function

<System.Runtime.CompilerServices.Extension()> _
Public Function Right(ByVal [string] As String, ByVal length As Integer) As String
    If length > [string].Length Then length = [string].Length
    Return [string].Substring([string].Length - length, length)
End Function