When you think ASP, think...
Recent Articles
All Articles
ASP.NET Articles
ASPFAQs.com
Message Board
Related Web Technologies
User Tips!
Coding Tips

Sections:
Sample Chapters
Commonly Asked Message Board Questions
JavaScript Tutorials
MSDN Communities Hub
Official Docs
Security
Stump the SQL Guru!
XML Info
Information:
Feedback
Author an Article
Technology Jobs
ASP ASP.NET ASP FAQs Message Board Feedback ASP Jobs

The 4 Guys Present: ASPFAQs.com

Jump to a FAQ
Enter FAQ #:
..or see our 10 Most Viewed FAQs.

4GuysFromRolla.com : ASP FAQS : Arrays


Question:

How can I quickly sort a VBScript array?


[Print this FAQ]

Answer: You could simply write your own sort algorithm (like a bubble sort) and encapsulate it in a function, however there's another way that's faster, while remaining very flexible. The key is using the JScript array's highly efficient sort method. Since VBScript and JScript arrays aren't directly interchangeable, we have to incur some overhead passing them back and forth. But the overhead is usually worth it.

First we define a JScript function that accepts a VBArray (a safeArray type), changes it to a JScript array and sorts it:

<script language=JScript runat=server>
    function SortVBArray(arrVBArray) {
        return arrVBArray.toArray().sort().join('\b');
    }
</script>


That's all there is to, it but here's the breakdown of the one line of code:
return Tells the function to return whatever comes to the right of it as the output of the function.

arrVBArray.toArray() Calls the toArray() method of the VBArray to convert it to a JScript array (this method is only available in JScript).

.sort() Since the expression to the left of this code evaluates to a Jscript array, we can now call the sort() method of it, to perform a case-sensitive ascending sort.

.join('\b'); This now joins the JScript array into a delimited string. The '\b' is a special non-printable character that is used as the delimiter because it will (almost) never appear in a string unlike other potential delmiters such as the comma. This is how it will be passed back to VBScript.

Next you need a VBScript function to "finish off" what this function couldn't do in JScript, convert the output to a VBScript array. It looks like this:

<%
    Function SortArray(arrInput)
        SortArray = Split(SortVBArray(arrInput), Chr(8))
    End Function
%>


Again only one line, this function uses the VBScript Split function to reconstitue the VBArray, now in sorted form. If you just wanted a sorted delimited string, you could call the SortVBArray() function directly.

The performance of this method is very good. Comparing executing time with a VBScript implementation of a bubble sort (shown below) gave the following results:

Array Size: 11 Items
SortArray: < 10ms
VB Bubble Sort: <10ms

Array Size: 211 Items
SortArray: 10ms
VB Bubble Sort: 160ms

Array Size: 1417 Items
SortArray: 30ms (!)
VB Bubble Sort: 7090ms

The larger the array, the more the savings with the .sort method. At 1417 items, it proves to be well over 200 times faster than even a very well implemented VB bubble sort!

VB bubble sort code:

<%
for i = UBound(arrShort) - 1 To 0 Step -1
    for j= 0 to i
        if arrShort(j)>arrShort(j+1) then
            temp=arrShort(j+1)
            arrShort(j+1)=arrShort(j)
            arrShort(j)=temp
        end if
    next
next %>


Happy Programming!


FAQ posted by Richard Lowe at 11/12/2000 1:58:42 AM to the Arrays category. This FAQ has been viewed 230,033 times.

Do you have a FAQ you'd like to suggest? Suggestions? Comments? If so, send it in! Also, if you'd like to be a FAQ Admin (creating/editing FAQs), let me know! If you are looking for other FAQs, be sure to check out the 4Guys FAQ and Commonly Asked Messageboard Questions!

Most Viewed FAQs:

1.) How can I format numbers and date/times using ASP.NET? For example, I want to format a number as a currency. (761643 views)
2.) I am using Access and getting a 80004005 error (or a [Microsoft][ODBC Microsoft Access Driver] The Microsoft Jet database engine cannot open the file '(unknown)' error) when trying to open a connection! How can I fix this problem? (207777 views)
3.) How can I convert a Recordset into an array? Also, how can I convert an array into a Recordset? (202549 views)
4.) How can I quickly sort a VBScript array? (196039 views)
5.) How can I find out if a record already exists in a database? If it doesn't, I want to add it. (156019 views)
6.) How do I display data on a web page using arrays instead of Do...While...MoveNext...???... (152331 views)
7.) When I get a list of all files in a directory via the FileSystemObject, they aren't ordered in any reasonable way. How can I sort the files by name? Or by size? Or by date created? Or... (140381 views)
8.) For session variables to work, must the Web visitor have cookies enabled? (110162 views)
9.) Can I send emails without using CDONTS? (107083 views)
10.) How can I take the result of a SELECT...MULTIPLE or a group of same-named checkboxes and turn it into a query? That is, if the user selects 3 answers, how can I construct a query that looks for all 3? (106308 views)
Last computed at 9/17/2007 3:22:00 AM

Software Developer / Programmer - Distributed Systems (NYC)
Next Step Systems
US-NY-New York

Justtechjobs.com Post A Job | Post A Resume


ASP.NET [1.x] [2.0] | ASPMessageboard.com | ASPFAQs.com | Advertise | Feedback | Author an Article