"Function" and "Sub" Procedures
This chapter provides tutorial examples and notes about function and subroutine procedures. Topics include defining function procedures and subroutine procedures, invoking procedures, passing arguments by reference or by value, checking scope of global and local variables.
What Is a Procedure?
"Function" Statement and Function Call
Function Procedure Example
"Sub" Statement and Subroutine Call
Sub (Subroutine) Procedure Example
Passing Arguments to Procedures
Example - Passing Arguments by Reference
Example - Passing Arguments by Value
Passing Arrays as Arguments
Variable Scope in Procedures
Example - Variable Scope in Procedures
- A "Function" statement defines a function procedure.
- A "Sub" statement defines a subroutine procedure.
- A function procedure provides the return value through the function name.
- A subroutine procedure will not return any values.
- An "Exit Function" or "Exit Sub" statement can be used to terminate a function procedure or a subroutine procedure.
- A "Call" statement can be used to invoke a subroutine procedure.
- The keyword "Call" is optional in a "Call" statement. If keyword "Call" is omitted,
the argument list can be specified without parentheses.
- A function procedure can be evaluated as part of an expression.
- A function procedure can also be evaluated with a "Call" statement.
- An argument is passed by reference, if it is defined with keyword "ByRef".
- But keyword "ByRef" is optional. So an argument is passed by reference by default.
- An argument is passed by value, if it is defined with keyword "ByVal".
- Variable defined in the main code is globally accessible in any procedure.
- Variable defined in a procedure is locally accessible only in that procedure.
- Recursive calling of a procedure is allowed.
- I don't know how to specify an array as the return value of a function procedure.
Table of Contents
About This Book
Introduction of VBScript - Visual Basic Scripting Edition
Variant Data Type, Subtypes, and Literals
Numeric Comparison Operations and Logical Operations
String Operations - Concatenation and Comparison
Variable Declaration and Assignment Statement
Expression and Order of Operation Precedence
Statement Syntax and Statement Types
Array Data Type and Related Statements
Array References and Array Assignment Statements
Conditional Statements - "If ... Then" and "Select Case"
Loop Statements - "For", "While", and "Do"
►"Function" and "Sub" Procedures
Inspecting Variables Received in Procedures
Error Handling Flag and the "Err" Object
Regular Expression Pattern Match and Replacement
scrrun.dll - Scripting Runtime DLL Library
Creating Your Own Classes
IE Web Browser Supporting VBScript
IIS ASP Server Supporting VBScript
WSH (Windows Script Host)
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