Migrating from Visual Basic

VisualBasic

Visual Basic (6 or earlier) and Visual Basic .NET use a language very similar to the Xojo language. You will notice that many of the commands are nearly the same, but there are differences as well.

You can find further information in these blog posts: A Modern Alternative to Visual Basic and Migrate Your Visual Basic Apps to Xojo and the Migrating to Visual Basic video.

To help make your transition from Visual Basic easier you can also download the open-source VB library which maps many VB commands to their Xojo equivalents for you:

Xojo.VB: A library of Visual Basic functions for use with the Xojo programming language.

Similarities to Visual Basic

Visual Basic 6 (VB6) is no longer supported by Microsoft, which recommends you instead migrate to Visual Basic .NET (VB.NET). But Visual Basic .NET is large and complex, not to mention not cross-platform. Xojo is usually a better choice for Visual Basic 6 apps because it has the simplicity of VB6, but is a fully object-oriented language like VB.NET.

Programming language

To start with, the language syntax of VB is very similar to Xojo. You 'll see familiar syntax for If...Then...Else, For...Next, While...Wend, Dim and many other commands. Someone who has used either VB6 or VB.NET will have no trouble understanding the Xojo programming language.

Data types

Although Xojo data types are not always named exactly the same as VB6 data types, all the equivalent types are there. For example, Integer is equivalent to a VB6 Long. Here is a mapping of some VB data types to Xojo data types:

VB Data Type	Xojo Data Type
Boolean	Boolean
Byte	UInt8
Currency	Currency
Date	DateTime class
Double	Double
Integer	Int16
Long	Integer
Object	Object
Single	Single
String	String
Variant	Variant

Commands

Below are some common VB commands and their corresponding Xojo commands.

String manipulation

VB Command	Xojo Command
Asc	String.Asc
Chr	String.ChrByte
Len	String.Length
Left	String.Left
Right	String.Right
Mid	String.Middle
Trim	String.Trim
LCase	String.Lowercase
UCase	String.Uppercase

Mathematical functions

VB Command	Xojo Command
Abs	Abs
Cos	Cos
Sin	Sin
Tan	Tan
Val	Val
Rnd	Rnd
Int	Floor

Input and output

VB Command	Xojo Command
MsgBox	MessageBox

Date and time

VB Command	Xojo Command
Date	DateTime
Time	DateTime
Timer	Timer

Miscellaneous

VB Command	Xojo Command
IsNull	Is Nil

File handling

VB Command	Xojo Command
Open	TextInputStream.Open, BinaryStream.Open

Controls

The default UI controls included with VB are, for the most part, also included with Xojo. But Xojo also has several controls that are not included by default with VB. Of course VB had plenty of additional, but Windows-specific, controls that could be added to its default setup and many of these controls can be added to Xojo using ActiveX, but they will also remain Windows-only.

Here is a list of some VB controls and their Xojo equivalents for desktop, web and iOS apps:

VB Control	Xojo Desktop Control	Xojo Web Control	Xojo Mobile Control
PictureBox	DesktopCanvas, DesktopImageViewer	WebCanvas, WebImageViewer	MobileCanvas MobileImageViewer
Label	DesktopLabel	WebLabel	MobileLabel
TextBox	DesktopTextField, DesktopTextArea	WebTextField, WebTextArea	MobileTextField, MobileTextArea
Frame	DesktopGroupBox	n/a	n/a
CommandButton	DesktopButton, DesktopBevelButton	WebButton	MobileButton
CheckBox	CheckBox	WebCheckBox	MobileSwitch
Listbox	DesktopListBox, DesktopPopupMenu	WebListBox, WebPopupMenu	iOSMobileTable
HScrollBar, VScrollBar	DesktopScrollbar	n/a	MobileScrollableArea
Timer	Timer	WebTimer	Timer
Shape	DesktopOval, DesktopRectangle	WebRectangle	MobileOval, MobileRectangle
WebBrowser	DesktopHTMLViewer	WebHTMLViewer	MobileHTMLViewer
TreeView	DesktopListBox	n/a	n/a
Toolbar	DesktopToolbar	WebToolbar	MobileToolbar
MediaPlayer	DesktopMoviePlayer	WebMoviePlayer	MobileHTMLViewer

Differences from Visual Basic

Xojo definitely feels familiar to VB developers, but there are differences as well. A big difference is that Xojo cannot create DLLs, ActiveX controls or any kind of shared libraries. Since these are all Windows-specific technologies, they are not useful for cross-platform apps.

Xojo can access DLLs and many ActiveX controls, but using them means your application will only run on Windows and cannot be cross-platform.

Of course, Xojo can easily create web and iOS apps, something VB6 cannot do.

File I/O

File input and output in VB6 uses direct, path-based access to files. This is not something that works for cross-platform apps, so Xojo consolidates all file processing into a few classes: FolderItem, TextInputStream, TextOutputStream and BinaryStream.

Data typing

Xojo is a strongly typed programming language. VB6 (and older versions) would allow you to use a variable that had not been previously declared. It would infer a type based on a special character in its name (name$ would be a String, for instance). Before trying to migrate VB6 code, you should use the OPTION EXPLICIT command to make sure that all your variables are declared.