Control Flow

Control-flow statements decide which code runs, how often it runs, and when the program should switch paths.

If

If <condition> Then
    <statements>
[ElseIf <condition> Then
    <statements> ...]
[Else
    <statements>]
End If

Then is required on If and ElseIf.
Else must appear alone on its line.
The terminator must be exactly End If.

An If condition must evaluate to True or False. Most conditions are built from comparisons such as score > 10 or lives = 0.

If score > highScore Then
    highScore = score
End If

If health <= 0 Then
    Print("Game Over")
Else
    Print("Keep going")
End If

You can combine tests with And, Or, and Not.

If score >= 100 And lives > 0 Then
    Print("Bonus round")
End If

If keyFound Or debugMode Then
    OpenDoor()
End If

If Not finished Then
    UpdateGame()
End If

If you are unsure how the condition part works, read Expressions for a beginner-friendly explanation of comparisons and operator precedence.

While

While <condition>
    <statements>
Wend

The condition is required.
Wend must appear alone on its line.

While lives > 0 And Not finished
    UpdateGame()
Wend

Do / Loop

Do
    <statements>
Loop

Do While <condition>
    <statements>
Loop

Do Until <condition>
    <statements>
Loop

Do
    <statements>
Loop While <condition>

Do
    <statements>
Loop Until <condition>

A condition may appear on Do or on Loop, but not both.
If While or Until is present, a condition is required.

For

For <identifier> = <startExpr> To <endExpr> [Step <stepExpr>]
    <statements>
Next [identifier]

To is required.
Step is optional.
Next may repeat the variable name.
If it does, the name must match the For variable.

Repeat / Until

Repeat
    <statements>
Until <condition>

Repeat must appear alone on its line.
Until requires a condition on the same line.

Repeat
    ReadInput()
Until choice <> 0

Select / Case

Select <expression>
Case <caseItem>[, <caseItem>...]
    <statements>
[Case Else
    <statements>]
End Select

<expression>
<startExpr> To <endExpr>

Case Else is supported.
Case lists may mix single values and ranges.
The terminator must be exactly End Select.