Is using 'not' better than using '= 0'

[norry]

Hi

When starting using Autoit I used to do the following for example;

If FileExists ("C:\afile.txt") = 0 Then

Is it better to use instead?

If Not FileExists ("C:\afile.txt") Then

Thanks

[Bert]

I would use

If FileExists ("C:afile.txt") = 0

for the command returns a value.

[Zedna]

If Not FileExists ("C:afile.txt") Then

I prefer this way a this way it has more readability

but from programers point of view it' the same.

[Bert]

As Zelda says you can do it that way also. Either way works.

Coding is an art....and a dark art at that!

[GEOSoft]

and just to throw a real wrench into the works; this will also work the same

If Not FileExists("C:afile.txt") = 1 then

[spudw2k]

I usually practice "not" as well

I just did a simple speed test and was slightly surprised to find =0 is faster by roughly 20% but were talking microseconds here.

edit:

Not =1 also is faster than just Not.....confused.

expandcollapse popup

_Test1()
_Test2()
_Test3()

Func _Test1()
    ConsoleWrite("Not" & @CRLF)
    $timer = TimerInit()
    If Not FileExists(@SystemDir) Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
    
    $timer = TimerInit()
    If Not FileExists("c:oogieboogie") Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
EndFunc

Func _Test2()
    ConsoleWrite("=0" & @CRLF)
    $timer = TimerInit()
    If FileExists(@SystemDir) = 0 Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
    
    $timer = TimerInit()
    If FileExists("c:oogieboogie") = 0 Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
EndFunc

Func _Test3()
    ConsoleWrite("Not =1" & @CRLF)
    $timer = TimerInit()
    If Not FileExists(@SystemDir) = 1 Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
    
    $timer = TimerInit()
    If Not FileExists("c:oogieboogie") = 1 Then
    
    EndIf
    ConsoleWrite(TimerDiff($timer) & @CRLF)
    $timer = 0
EndFunc

Edited April 20, 2012 by spudw2k

[guinness]

spudw2k,

I found this to be the case as well sometime ago, Not does make it easier to read but I try to use ' = 0' when I can.

[guinness]

Another one is single line If statements >>

Local $iTimer, $iVariable = 1

$iTimer = TimerInit()
For $A = 1 To 100000
    If $iVariable Then $iVariable = 1
Next
ConsoleWrite(Round(TimerDiff($iTimer), 2) & @CRLF) ; Average = 0.00830911064656123

$iTimer = TimerInit()
For $A = 1 To 100000
    If $iVariable Then
        $iVariable = 1
    EndIf
Next
ConsoleWrite(Round(TimerDiff($iTimer), 2) & @CRLF) ; Average = 0.00586525457404322

[spudw2k]

very interesting. if the differences were beyond microseconds I'd probably change my coding practices, but this has opened my eyes to the fact that while I may have two seemly identical routines to accomplish the same task, one might be more efficient.

Thanks for sharing

[Morthawt]

I personally prefer the: If Not FileExists ("C:afile.txt") Then method.

[KaFu]

Not =1 also is faster than just Not.....confused.

Seems like there is some initialization work being done under the hood, just shuffle the function calls and make more iterations.

expandcollapse popup

_Test3()
_Test3()
_Test1()
_Test2()


Func _Test1()
    ConsoleWrite("Not" & @CRLF)
    $timer1 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists(@SystemDir) Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer1) & @CRLF)

    $timer2 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists("c:oogieboogie") Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer2) & @CRLF)

EndFunc   ;==>_Test1

Func _Test2()
    ConsoleWrite("=0" & @CRLF)
    $timer1 = TimerInit()
    For $i = 1 To 10000
        If FileExists(@SystemDir) = 0 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer1) & @CRLF)


    $timer2 = TimerInit()
    For $i = 1 To 10000
        If FileExists("c:oogieboogie") = 0 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer2) & @CRLF)

EndFunc   ;==>_Test2

Func _Test3()
    ConsoleWrite("Not =1" & @CRLF)
    $timer1 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists(@SystemDir) = 1 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer1) & @CRLF)


    $timer2 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists("c:oogieboogie") = 1 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer2) & @CRLF)

EndFunc   ;==>_Test3

[MvGulik]

Seems like there is some initialization work being done under the hood,

Yes there is.

Seeing speed test that seem to ignore that little fact always bother me.

Not seen yet:

If FileExists("C:afile.txt") then

else

[guinness]

I've found on my system If FileExists(@ScriptDir) = 0 Then and If FileExists(@ScriptDir) Then to be the speediest!!

[PhoenixXL]

Hey Norry

as u may get a bit confused because eveyone have their own opinion so am I

Anyways I will like to clear your doubt

If u check the operators part in the help file u will find that 'NOT' is listed above all.........

Its also the fastest option .........

U can use either way both are the same But using 'NOT' is a better option

Since even a single microsecond is important in computers

Regards

Phoenix XL

[guinness]

Its also the fastest option .........

How did you draw this conclusion?

[PhoenixXL]

Hey Guinness

U can use Timer Functions to find it out ..........

Figure it out by the values returned

_Test1()
_Test2()

Func _Test1()
    ConsoleWrite("Not=" & @TAB)
    $timer1 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists(@SystemDir) Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer1) & @CRLF)
ConsoleWrite("=0" & @TAB)
    $timer2 = TimerInit()
    For $i = 1 To 10000
        If FileExists(@SystemDir)=0 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer2) & @CRLF)
EndFunc   ;==>_Test1
Func _Test2()
    ConsoleWrite("Not=" & @TAB)
    $timer1 = TimerInit()
    For $i = 1 To 10000
        If Not FileExists('c:oogieboogie') Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer1) & @CRLF)
ConsoleWrite("=0" & @TAB)
    $timer2 = TimerInit()
    For $i = 1 To 10000
        If FileExists("c:oogieboogie") = 0 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer2) & @CRLF)
EndFunc   ;==>_Test2

Tried 15 Times on my system

and Each and Every Time the Not was Fastest

Edited April 21, 2012 by PhoenixXL

[guinness]

Your test gave me this >>

Not= 412.02056573866

=0 390.80573256035

Not= 626.157238259234

=0 603.384675992839

[PhoenixXL]

Sorry Guinness but on My Computer its just the Opposite

Im Having Intel Core 2 Duo

2 GB Ram and Windows 7 32 Bit..............

I replied according to the results i got

Sorry if i provided with wrong information

[Kealper]

That speed test is flawed because it's relying on FileExists, which has to use the hard drive. Using the hard drive in any way will provide inaccurate results, since it can be artificially higher if the hard drive had to read elsewhere while the program was running, and because of hard drive caching. You want to stick with as simple as you can to get the best result for speed... I used this modified code below and got the result

Control 77.339361134457

Control 70.0860663838289

Not 88.6980408713137

= 0 119.18438789057

Not 89.8022169750838

= 0 116.691032824602

It seems from this more stripped down test, Not is faster than = 0 when spread out over 100k calls... The two "Control" things in there are 100k checks of just "If True Then"

Modified speed test code:

Control()
Control()
Test1()
Test2()
Test1()
Test2()

Func Test1()
    ConsoleWrite("Not" & @TAB)
    $timer = TimerInit()
    For $i = 1 To 100000
        If Not True Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer) & @CRLF)
EndFunc

Func Test2()
    ConsoleWrite("= 0" & @TAB)
    $timer = TimerInit()
    For $i = 1 To 100000
        If Not True = 0 Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer) & @CRLF)
EndFunc

Func Control()
    ConsoleWrite("Control" & @TAB)
    $timer = TimerInit()
    For $i = 1 To 100000
        If True Then
        EndIf
    Next
    ConsoleWrite(TimerDiff($timer) & @CRLF)
EndFunc

EDIT: We should probably also say the CPU/RAM speed we have, since that could very well make a difference..

I've got a 1.83Ghz Intel Core 2 Duo with DDR2-667 ram.

Edited April 21, 2012 by Kealper

[MvGulik]

That speed test is flawed because it's relying on FileExists,

Flawed is a big word. But yea, in speed tests you should try to minimize/optimize the test to eliminate unneeded additional variations.

FileExists: could (ok, will) most of the time use the disk cached data instead of actually firing a physical disk check.

Edited April 21, 2012 by MvGulik