VB.Net - If...Then...Else语句

Module decisions
   Sub Main()
       'local variable definition '
      Dim a As Integer = 100
      ' check the boolean condition using if statement 
      If (a < 20) Then
          ' if condition is true then print the following 
          Console.WriteLine("a is less than 20")
      Else
          ' if condition is false then print the following 
          Console.WriteLine("a is not less than 20")
      End If
      Console.WriteLine("value of a is : {0}", a)
      Console.ReadLine()
   End Sub
End Module

a is not less than 20
value of a is : 100

语法：

If(boolean_expression 1)Then
   ' Executes when the boolean expression 1 is true 
ElseIf( boolean_expression 2)Then
   ' Executes when the boolean expression 2 is true 
ElseIf( boolean_expression 3)Then
   ' Executes when the boolean expression 3 is true 
Else 
   ' executes when the none of the above condition is true 
End If

Module decisions
   Sub Main()
      'local variable definition '
      Dim a As Integer = 100
      ' check the boolean condition '
      If (a = 10) Then
          ' if condition is true then print the following '
          Console.WriteLine("Value of a is 10") '
      ElseIf (a = 20) Then
          'if else if condition is true '
          Console.WriteLine("Value of a is 20") '
      ElseIf (a = 30) Then
          'if else if condition is true  
          Console.WriteLine("Value of a is 30")
      Else
          'if none of the conditions is true 
          Console.WriteLine("None of the values is matching")
      End If
      Console.WriteLine("Exact value of a is: {0}", a)
      Console.ReadLine()
   End Sub
End Module

None of the values is matching
Exact value of a is: 100