7.1.9 Sub

Purpose

Declares the name and arguments, and indicates the start of the Sub procedure. It also defines a sequence of statements enclosed by the Sub statement and End Sub statement as a Sub procedure.

Syntax

Sub Name [(ArgList)]
  [Statements]
  [Exit Sub]
  [Statements]
End [Sub]

Arguments

Name

Write the name of the Sub procedure you are defining. Comply with the variable naming conventions.

ArgList

Specify a list of variables representing the arguments to pass to the Sub procedure when it is called. Delimit multiple variables with commas. Enclose any arguments with parentheses.

Statements

Write a group of statements to be executed within the Sub procedure.

Description

Sub procedures are public and can be referenced by all other procedures in the script.

The executable code must be written entirely within the procedure. You cannot define a Sub procedure inside another Sub procedure or inside a Function procedure.

The Exit Sub statement causes the program to immediately exit from a Sub procedure. Execution continues from the statement following the statement that called the Sub procedure. You can write any number of Exit Sub statements as required anywhere in a Sub procedure.

Because the Sub procedure does not return a value, Sub procedure names cannot be used in expressions, statements, or commands.

To call a Sub procedure, write the procedure name followed by an argument list. For details on calling Sub procedures, see 7.1.10 Call.

Two types of variables can be used in Sub procedures: variables that are explicitly declared within the procedure and those that are not. Variables that are explicitly declared in a procedure, using the Dim command or equivalent, behave as local variables that are valid only within that procedure. Variables that are used but not explicitly declared in a procedure are also local unless they are explicitly declared at some higher level outside the procedure. The value of local variables in a Sub procedure are discarded when the procedure finishes execution.

A variable that is not explicitly declared in the procedure can be used in a Sub procedure, but it will be handled as a global variable if another variable or entity is defined at the script level with the same name as the undeclared variable.

Example

' Call the Sub procedure OperateMessage
' that displays a message dialog box.
Dim Task
Task = "file update"
 
Call OperateMessage("Start")
           : 
Call OperateMessage("Stop")
 
Sub OperateMessage(status)
    Dim stamp
    stamp = Date + " " + Time
    MessageBox( "" & status & "" & Task & " at " & stamp)
End Sub

JP1/Script version

Supported from JP1/Script 01-00.

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