Jump to content

Little programming exercise


 Share

Recommended Posts

Just wanted to waste some time and converted some php code to AutoIt :

$primeNumbers = array();
$output = '';
$start = microtime(TRUE);
for ($i = 2; $i < 100000; $i++)
{
     $divisible = false;
     foreach ($primeNumbers as $number)
     {
             if ($i % $number == 0)
             {
                     $divisible = true;
                     break;
             }
     }
     if ($divisible == false)
     {
             $primeNumbers[] = $i;
             $output .= $i;
     }
}
echo count($primeNumbers), "n";
echo "time: ", microtime(TRUE) - $start, "n";

#include <Array.au3>

Dim $primes[1]
Local $number
$output = ''

For $i = 2 To 100000
$divisible = false

For $number In $primes
If Mod($i, $number) = 0 Then
$divisible = true
ExitLoop
EndIf
Next

if $divisible = false Then
_ArrayAdd($primes, $i)
$output &= $i
EndIf
Next

MsgBox(0,'',UBound($primes))

Well, except the timing functions which I decided there's no reason to add after I ran it lol , would you say this code is equivalent ? It returns the same number of results (plus one, I guess it's the initialization I had to use ?) so I guess it runs fine.

EDIT: AutoIt code tag my ass ....

Edited by Inverted
Link to comment
Share on other sites

Well, except 2

This wonderful site allows debugging and testing regular expressions (many flavors available). An absolute must have in your bookmarks.
Another excellent RegExp tutorial. Don't forget downloading your copy of up-to-date pcretest.exe and pcregrep.exe here
RegExp tutorial: enough to get started
PCRE v8.33 regexp documentation latest available release and currently implemented in AutoIt beta.

SQLitespeed is another feature-rich premier SQLite manager (includes import/export). Well worth a try.
SQLite Expert (freeware Personal Edition or payware Pro version) is a very useful SQLite database manager.
An excellent eBook covering almost every aspect of SQLite3: a must-read for anyone doing serious work.
SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
A work-in-progress SQLite3 tutorial. Don't miss other LxyzTHW pages!
SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

Link to comment
Share on other sites

I guess setting step to 2 would be a good start, but what matters, is that the algorithm is as much the same as possible, for comparison's sake.

If I understanf correctly, constantly using ArrayAdd is the main performance hog, because it has to ReDim the array ? Or am I wrong ?

What is a more efficient alternative to the way I do the array operations ?

Link to comment
Share on other sites

  • Moderators

Inverted,

What is a more efficient alternative to the way I do the array operations ?

Take a look at the last example in the Recursion tutorial in the Wiki and the text beneath it. ;)

M23

Public_Domain.png.2d871819fcb9957cf44f4514551a2935.png Any of my own code posted anywhere on the forum is available for use by others without any restriction of any kind

Open spoiler to see my UDFs:

Spoiler

ArrayMultiColSort ---- Sort arrays on multiple columns
ChooseFileFolder ---- Single and multiple selections from specified path treeview listing
Date_Time_Convert -- Easily convert date/time formats, including the language used
ExtMsgBox --------- A highly customisable replacement for MsgBox
GUIExtender -------- Extend and retract multiple sections within a GUI
GUIFrame ---------- Subdivide GUIs into many adjustable frames
GUIListViewEx ------- Insert, delete, move, drag, sort, edit and colour ListView items
GUITreeViewEx ------ Check/clear parent and child checkboxes in a TreeView
Marquee ----------- Scrolling tickertape GUIs
NoFocusLines ------- Remove the dotted focus lines from buttons, sliders, radios and checkboxes
Notify ------------- Small notifications on the edge of the display
Scrollbars ----------Automatically sized scrollbars with a single command
StringSize ---------- Automatically size controls to fit text
Toast -------------- Small GUIs which pop out of the notification area

 

Link to comment
Share on other sites

I'd think preallocating your array, and then a single redim at the end would be the way to go:

#include <Array.au3>

Local $max = 1000, $primes[100 + $max * .17] = [2], $idx

For $i = 3 To $max Step 2
    For $j = 0 to $idx
        $rem = Mod($i, $primes[$j])
     If $rem = 0 Then ExitLoop
    Next
    If $rem Then
     $idx += 1
     $primes[$idx] = $i
    EndIf
Next
ReDim $primes[$idx + 1]
_ArrayDisplay($primes, $idx + 1 & " found")

edit: trying to tune the preallocated array size

Edited by Spiff59
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...