VBScript Tutorials - Herong's Tutorial Notes
Dr. Herong Yang, Version 4.01

Procedures - Functions and Subroutines

Part:   1  2  3  4  5   6 

VB Script Tutorials - Herong's Tutorial Notes © Dr. Herong Yang

Data Types and Literals

Variables

Logic Operations

String Operations

Conditional Statements

Arrays

Loop Statements

Functions and Subroutines

Built-in Functions

Variable Inspection

... Table of Contents

(Continued from previous part...)

Here is the output: 


Test 1: Swapping two literals by value
   Before Sub: Apple | Orange
   In Sub: Orange | Apple
   After Sub: Apple | Orange

Test 2: Swapping two variables by value
   Before Sub: Dog | Cat
   In Sub: Cat | Dog
   After Sub: Dog | Cat

Here are my comments about this example:

  • Test 1 is useless.
  • Test 2 shows that "ByVel" arguments will not bring any changes back to the calling code. After the subroutine call, values in vFirst and vSecond have not been changed at all.

Passing Array as Arguments

As I mentioned earlier, arrays can also be passed as arguments. If an array is passed by reference, the procedure is working on the same array as the calling code. If an array is passed by value, the procedure is working on a independent copy of the array in the calling code.

Here is an example code of using array as an argument, function_reverse_array.html: 

<html>
<body>
<!-- function_reverse_array.html
   Copyright (c) 2006 by Dr. Herong Yang. http://www.herongyang.com/
-->
<pre>
<script language="vbscript">
   document.writeln("")
   document.writeln("Test 1: Reversing a data literal")
   bOk = ReverseArray("Apple")

   aPets = Array("Bird", "Cat", "Dog", "Fish", "Rabbit")
   document.writeln("")
   document.writeln("Test 2: Reversing an array")
   document.writeln("   Before Sub: " & Join(aPets))
   bOk = ReverseArray(aPets)
   document.writeln("   After Sub: " & Join(aPets))

Function ReverseArray(ByRef aList)
   If IsArray(aList) Then
      iMin = LBound(aList)
      iMax = UBound(aList)
      For i=iMin to iMax\2
         j = iMax - (i-iMin) 
         vTemp = aList(i)
         aList(i) = aList(j)
         aList(j) = vTemp
      Next
      ReverseArray = True
   Else
      document.writeln("Error: You are not giving an array.")
      ReverseArray = False
   End If
End Function
</script>
</pre>
</body>
</html>

Here is the output: 


Test 1: Reversing a data literal
Error: You are not giving an array.

Test 2: Reversing an array
   Before Sub: Bird Cat Dog Fish Rabbit
   After Sub: Rabbit Fish Dog Cat Bird

My "ReverseArray" function worked perfectly. You can take it a utility function to your application.

(Continued on next part...)

Part:   1  2  3  4  5   6 

Dr. Herong Yang, updated in 2006
VBScript Tutorials - Herong's Tutorial Notes - Procedures - Functions and Subroutines