Conditional statements

If

The If statement allows you to conditionally execute a block of statements depending on the result of a series of boolean expressions.

The first boolean expression that evaluates to true will cause the associated block of statements to be executed. No further boolean expressions will be evaluated.

If no boolean expression evaluates to True, then the final else block will be executed if present.

The syntax for the If statement is:

If expression [ Then ]

    Statements...

ElseIf expression [ Then ]

    Statements...

Else

    Statements...

EndIf

There may be any number of ElseIf blocks, or none. The final Else block is optional.

End or End If may be used instead of EndIf, and Else If may be used instead of ElseIf.

In addition, a simple one line version of If is also supported:

If Expression [ Then ] Statement [ Else Statement ]

Select

The Select statement allows you to execute a block of statements depending on a series of comparisons.

The first comparison to produce a match will cause the associated block of statements to be executed.

If no comparisons produce a match, then the final Default block will be executed if present.

The syntax for the Select statement is:

Select Expression

    Case Expression [ , Expression... ]

        Statements...

    Default

        Statements...

End [ Select ]

There may be any number of Case blocks, or none. The final Default block is optional. If the default block is present, it must appear after all Case blocks.

? Else

The ? Else operator is used to assign a value with a condition:

variable = Expression ? Expression-A Else Expression-B

The variable will receive the value of Expression-A if Expression is True, else it will receive the value of Expression-B.

The following example:
i = j>2 ? 5 Else j+7
is the same as writing:

If j>2
    i = 5
Else
    i = j+7
EndIf

?Else

The 'Elvis operator' ?Else can be used to return an alternate value if an expression is null.

variable = Expression ?Else Expression-B

For example:

r = x ?Else -1

This will assign the value of x to r if x is non-null.
Otherwise it will assign the value -1 to r.