Cross Ref > Language Basics

VB.Net is not case sensitive. If you type any other case for commands or variables, VB.Net will change it to the accepted or defined case. For example, if you type messagebox.show it is converted to MessageBox.Show.

Syntax Example:   The following code works: MessageBox.Show("hello")

ASP Classic is not case sensitive. My preference for all languages where case sensitivity does not matter is to use camel caps as in the first example above. Many developers coming from a case sensitive language prefer to use all lowercase.

Syntax Example:   You can use any of the following: Response.Write "Hello" response.write "Hello" RESPONSE.WRITE "Hello" REsponse.WritE "Hello"

VB.Net, like VB Classic code blocks, are surrounded by statement ending keywords that all use End such as End Class, End Sub, End Function, and End If.

Public Class Dog

End Class

Protected Sub MySub

End Sub

Public Shared Function MySharedFunction() As Integer
 MySharedFunction = 12345
End Function 

If x Then

End If

In .ASP html pages, you embed ASP code between <% and %>.

ASP Classic code blocks are surrounded by statement ending keywords that all use End such as End Sub, End If, and WEnd.

<%

Sub x

End Sub

If x Then

End If

While x

WEnd

%>

Commenting Code
VB.Net, like all the VB-based languages, uses a single quote (') or the original class-style basic "REM" (most developers just use a quote). VB.Net does NOT have a multiple line comment.

'Single line comment.
 

REM Old school single line comment.

 VB.Net Comments (' or REM)  

Commenting Code
ASP Classic, like all the VB-based languages, uses a single quote (') or the original class-style basic "REM" (most developers just use a quote). ASP Classic does NOT have a multiple line comment.

Preprocessor Directives - @ and #
An @ is used for preprocessor directives within ASP code (within <% %>) and a # is used for HTML-style preprocessor directives.

Note: ASP Classic does not support VB Classic's #If directive.

'Single line comment.

REM Old school single line comment.

<%@LANGUAGE=VBScript%>

<!-- #Include File="includes.inc" -->

 ASP Classic Comments (' or REM)

In VB.Net, you define constants with the Const keyword.

All constants are part of a class (no global constants) but you can make a constant public and have access to it using ClassName.ConstantName so long as you have added the class to the project. This works even without creating the class as if the public constants were static, but you cannot use the Shared keyword.

Constants must be of an integral type (sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal, bool, or string), an enumeration, or a reference to null.

Public Class Convert
  Inherits System.Object

  Public Const kName As String = "Mike"

  Private Const kPI Double = 3.1459

  //Declare two or more on same line too:
  Const kFeetToMeter = 3.2808, kMeterToFeet = 0.3048
End Class

 VB.Net Constants (Const kPI Double = 3.1459)  

Scope can be Public or Private. Public Const is the same as just specifying Const. As with variables, all constants are variants. You do not specify the type, it's implied.

Const kPI = 3.1459

Const kName = "Mike"

//Public variable:

Public Const kFeetToMeter=3.28, kMeterToFeet=.3

 ASP Classic Constants (Const kPI = 3.1459)

A return marks the end of a statement and you cannot combine statements on a single line of code. You can break a single statement into two or more code lines by using a space and underscore " _".

Syntax Example:   Console.WriteLine("Hello1") Console.WriteLine("Hello2") Console.WriteLine("Hello3") 'The following commented code 'on a single line does not work... 'Console.WriteLine("Hello4") Console.WriteLine("Hello5") 'Two or more lines works too with a space+underscore: Console.WriteLine _ "Hello6";

A return marks the end of a statement and you cannot combine statements on a single line of code. You can break a single statement into two or more code lines by using a space and underscore " _".

Response.Write("Hello1")
Response.Write("Hello2")
Response.Write("Hello3")
 
'The following commented code on a single line does not work...
' Response.Write("Hello4")  Response.Write("Hello5")
 
'Two or more lines works too with a space+underscore:
Response.Write _
  ("Hello6")

String literals are quoted as in "Prestwood". If you need to embed a quote use two quotes in a row.

To specify a floating point literal between 1 and -1, preceed the decimal with a 0. If you don't, the compiler will auto-correct your code and place a leading 0. It will change .1 to 0.1 automatically. Trailing decimals are not allowed.

Syntax Example:   Console.WriteLine("Hello") Console.WriteLine("Hello ""Mike"".") 'Does VB.Net evaluate this simple 'floating point math correctly? No!  If (.1 + .1 + .1) = 0.3 Then MsgBox "Correct" Else MsgBox "Not correct" End If

String literals are quoted as in "Prestwood". If you need to embed a quote use two quotes in a row.

To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).

Response.Write "Hello"

Response.Write "Hello ""Mike""."

'Does ASP evaluate this simple

'floating point math correctly? No! 

If (.1 + .1 + .1) = .3 Then
 Response.Write "Correct"
Else
 Response.Write "Not correct"
End If

Variables are case sensitive but VS.Net will auto-fix your variable names to the defined case. You can declare variables in-line wherever you need them and declarative variable assignment is supported.

Syntax Example:   Dim FullName As String Dim Age As Integer Dim Weight As Double FullName = "Mike Prestwood" Age = 32 Weight = 154.4 'Declaritive variable assignment: Dim Married As String = "Y" MsgBox(Married)

ASP Classic is a loosely typed language. No variable types in ASP (all variables are variants). Declaring variables is even optional unless you use the Option Explicit statement to force explicit declaration of all variables with Dim in that script. Using Option Explicit is strongly recommended to avoid incorrectly typing an existing variable and to avoid any confusion about variable scope.

For example, at the top of my common include file, I have the following:

<%@LANGUAGE=VBScript%>
<%
Option Explicit
'...more code here.

%>

Dim Fullname
Dim Age

Dim Weight

FullName = "Mike Prestwood"

Age = 32

Weight = 154.4

'Declaritive assignment not supported:

''Dim Married = "Y"   '>>>Not supported.