Lingo in a Nutshell

Conditional Execution

You can have Director execute different Lingo code in response to various conditions. Any non-zero expression (including negative numbers) is considered TRUE, and only an expression that evaluates to zero is considered FALSE. Refer to Chapter 5 for details on evaluating comparisons, including compound expressions. (These example multi-line code fragments must be placed in a handler for testing.)

If...Then...Else...End If Decisions

The if statement will execute different Lingo code based on the value of the specified expression. This allows you to, say, use a single Director movie on both Macintosh and Windows but branch to different code depending on the playback platform, as determined by the platform property, such as:

if (the platform starts "Windows") then
  -- Do Windows-specific stuff here
else
  -- Do Macintosh-specific stuff here
end if

The if statement has many possible forms, but I recommend only these. Items shown in curly braces are optional. Note the correct indentation:

Single-Clause If...Then...End If

if expression then
  statement1
  statement2
end if

Multiple-Clause If...Then...Else If...Else...End If

The else if and else clauses are optional:

if expression then
   statement1
{else if expression then
   statement2}
{else
   defaultAction}
end if

For example:

if x = 1 then
  go frame "Slide1"
else if x = 2 then
  go frame "Slide2"
else if x = 3 then
  go frame "Slide3"
else
  go frame "End"
end if

One-Line and Two-Line If Statements

The following forms are theoretically valid, but ...