VB.Net Tutorial/Development/Pre Compile

#Const

<source lang="vbnet">public class Test

  public Shared Sub Main
       #If UseFastAlgorithm Then
           Console.WriteLine("Fast")
       #Else
           Console.WriteLine("Slow")
       #End If
       
       #Const UseFastAlgorithm = True
       
       #If UseFastAlgorithm Then
          Console.WriteLine("Fast")
       #Else
          Console.WriteLine("Slow")
       #End If
  End Sub

End class</source>

Slow
Fast

#ElseIf

<source lang="vbnet">public class Test

  public Shared Sub Main

1. If CONFIG = "Debug" Then

       Console.WriteLine("Debug")

1. ElseIf CONFIG = "Release" Then

       Console.WriteLine("Release")

1. ElseIf CONFIG = "InterimBuild" Then

       Console.WriteLine("InterimBuild")

1. Else

       Console.WriteLine("Unknown build type")

1. End If

  End Sub

End class</source>

Very Good.

#if, #Else, #End If

<source lang="vbnet">public class Test

  public Shared Sub Main
       #If UseFastAlgorithm Then
           Console.WriteLine("Fast")
       #Else
           Console.WriteLine("Slow")
       #End If
       
       #Const UseFastAlgorithm = True
       
       #If UseFastAlgorithm Then
          Console.WriteLine("Fast")
       #Else
          Console.WriteLine("Slow")
       #End If
  End Sub

End class</source>

Slow
Fast