VBScript Tutorials - Herong's Tutorial Examples

∟"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

Conclusions

• 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

 Arithmetic Operations

 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

 Built-in Functions

 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)

 References

 Printable Copy - PDF Version