Solved

How to do a reverse sort (descending) of filenames using Quicksort function?

Posted on 2006-10-26
4
1,264 Views
Last Modified: 2011-10-03
I'm having a problem trying to do a reverse sort (descending order; Z to A; n to 0).
The Quicksort function (mentioned below) does a sort in ascending order (A to Z; 0 to n) and is an excerpt from a C++ book called "Data Abstractions & Structures using C++". I've used the following code to do a sort of filenames/folders in a customized Enhanced Browser Page for IIS 5.0 and WORKS!!! I've tried to manipulate variables within the function to do a reverse sort however I've had no luck....

My question:  How/What do I change the Quicksort function (execerpt below) to sort in descending order (Z to A; n to 0)?

'___________________________________________________________________
Sub QuickSort(vec,loBound,hiBound,SortField)
  '==--------------------------------------------------------==
  '== Sort a 2 dimensional array on SortField                ==
  '==                                                        ==
  '== This procedure is adapted from the algorithm given in: ==
  '==    ~ Data Abstractions & Structures using C++ by ~     ==
  '==    ~ Mark Headington and David Riley, pg. 586    ~     ==
  '== Quicksort is the fastest array sorting routine For     ==
  '== unordered arrays.  Its big O is  n log n               ==
  '==                                                        ==
  '== Parameters:                                            ==
  '== vec       - array to be sorted                         ==
  '== SortField - The field to sort on (2nd dimension value) ==
  '== loBound and hiBound are simply the upper and lower     ==
  '==   bounds of the array's 1st dimension.  It's probably  ==
  '==   easiest to use the LBound and UBound functions to    ==
  '==   Set these.                                           ==
  '==--------------------------------------------------------==

  Dim pivot(),loSwap,hiSwap,temp,counter
  Redim pivot (Ubound(vec,2))
  '== Two items to sort
  if hiBound - loBound = 1 then
    if vec(loBound,SortField) > vec(hiBound,SortField) then
      Call SwapRows(vec,hiBound,loBound)
    End If
  End If
0
Comment
Question by:HCAAdmin
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
4 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 17816036
if vec(loBound,SortField) < vec(hiBound,SortField) then
0
 

Author Comment

by:HCAAdmin
ID: 17821841
Thanks for the reply....

However it still doesn't seem to work. Perhaps I need to change something in the subroutine called "Swaprows"?
The following is the subroutine called within the Quicksort() function:

Parameters being passed into the subroutine:
SwapRows(vec,hiBound,loBound)
-------------------------------------------------------------
Sub SwapRows(ary,row1,row2)
  '== This proc swaps two rows of an array
  Dim x,tempvar
  For x = 0 to Ubound(ary,2)
    tempvar = ary(row1,x)    
    ary(row1,x) = ary(row2,x)
    ary(row2,x) = tempvar
      
  Next
0
 
LVL 44

Accepted Solution

by:
Arthur_Wood earned 250 total points
ID: 17822057
try this change:

  Dim pivot(),loSwap,hiSwap,temp,counter
  Redim pivot (Ubound(vec,2))
  '== Two items to sort
  if hiBound - loBound = 1 then
    if vec(loBound,SortField) < vec(hiBound,SortField) then
      Call SwapRows(vec,loBound,hiBound)
    End If
  End If

AW
0
 

Author Comment

by:HCAAdmin
ID: 17833631
I got an answer to this question....

Check out the response to my post! http://www.experts-exchange.com/Web/Q_22039210.html

Thanks for the effort and I will offer some points! :)
0

Featured Post

[Webinar] Code, Load, and Grow

Managing multiple websites, servers, applications, and security on a daily basis? Join us for a webinar on May 25th to learn how to simplify administration and management of virtual hosts for IT admins, create a secure environment, and deploy code more effectively and frequently.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Navigation is an important part of web design from a usability perspective. But it is often a pain when it comes to a developer’s perspective. By navigation, it often means menuing. This is less theory and more practical of how to get a specific gro…
This article is meant to give a basic understanding of how to use R Sweave as a way to merge LaTeX and R code seamlessly into one presentable document.
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question