global or local declaration in a loop = inefficient?

[Imbuter2000]

Is there difference in speed/efficiency between the following two solutions?

local $foobar

for $i = 1 to 1000

$foobar = "house"

do_this_and_that...

next

____

for $i = 1 to 1000

local $foobar = "house"

do_this_and_that...

next

____

note: I visually prefer to set the value inside the function instead than on the top in my real case because I need it in the middle of a long function....

[bogQ]

spid isnt important heare, you do not have any need to redeclare it as local if its declared as local once. so your fitst way is correct way to go and probably faster.

first

9.32017896129257

second

27.1844605948521

Sleep(1000)
$a = TimerInit()
local $foobar
for $i = 1 to 10000
    $foobar = "house"
next
ConsoleWrite(TimerDiff($a)&@CRLF)
$b = TimerInit()
for $i = 1 to 10000
    local $foobax = "house"
next
ConsoleWrite(TimerDiff($b)&@CRLF)

Edited December 19, 2012 by bogQ

[guinness]

Variables should be declared and initialised outside of loops.

[water]

If you want to know which is faster use _TimerInit and _TimerDiff to measure it.

[bogQ]

whats wrong with TimerInit() vs _TimerInit ?

[water]

Nothing is wrong with TimerInit. _TimerInit was just the first which came to my mind

[bogQ]

ohh so it was not directed to code in my post

[water]

No, it wasn't. Actually I have only read the OPs post but didn't read all following posts in detail.

[guinness]

The reason for the decrease in speed is because AutoIt internally checks if the variable has been declared before, do this over again and again in quick succession will show an "unnoticeable" decrease in speed.

[Imbuter2000]

ok, got all. Just a question: are we talking only about a speed difference of 18ms for 10000 re-declarations?

[BrewManNH]

In this example on that computer, it appears so.

It's still bad coding practice to do it that way, and totally avoidable so why bother doing it?

[Imbuter2000]

because for what can be only 1 line of code in the middle of a long cycle I'm not convinced that it's better practice to add a second line of related code and far from it/out of my immediate view.

Considering that the re-declaration is a so small inefficiency.

[DicatoroftheUSA]

because for what can be only 1 line of code in the middle of a long cycle I'm not convinced that it's better practice to add a second line of related code and far from it/out of my immediate view.

Considering that the re-declaration is a so small inefficiency.

Add the following to your script if you are worried about variables being declared and not used. Also if you are naming your variables, they should be self evident of their purpose (at very least to you) so if it all the variables are declared at the begining and named well, it actually makes the script tidear and easier to read by giving clues to how the function operates.

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w 4 -w 5 -w 6

Edited December 19, 2012 by DicatoroftheUSA