Compaisons: Int Numbers An Strings, The Fastest ?

[Manus-Magnus]

hello,

Basicly it's optimisation support request... Or general C programming question...

I have some function burning my CPU comparing variables with constant numbers.

have have multiples ways to exit a loop but...

What is the order from the fastest to the slowest compares with (i need order with all not the 1 fastest in this list):

If $x <> [int number] then....

If $x < [int number] then....

If $x > [int number] then....

If $x == [int number] then....

If $x >= [int number] then....

If $x <= [int number] then....

The next question is: same thing but with strings.

Edited January 22, 2004 by Manus-Magnus

[MattNis]

Seems like ">" is the fastest

expandcollapse popup

$start = TimerStart()

For $i = 0 To 262144
    if $i == 262144 then $x=0
Next

$equal = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i >= 262144 then $x=0
Next

$ge = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i <= 262144 then $x=0
Next

$le = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i NOT = 262144 then $x=0
Next

$ne = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i < 262144 then $x=0
Next

$less = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i > 262144 then $x=0
Next

$greater = TimerStop($start) / 1000

MsgBox(4096, "Execution time:", "==" & $equal & @LF & ">=" & $ge & @LF & "<=" & $le & @LF & "NOT=" & $ne & @LF & "<" & $less & @LF & ">" & $greater)

Edited January 23, 2004 by MattNis

[Valik]

There are several things wrong with that test. First, == forces a string comparison, this adds tremendous overhead since it's doing a string compare instead of double compare.

Secondly, the Not = test is done incorrectly. Not doesn't work like that Try this to prove it:

If 1 Not = 2 Then MsgBox(4096, "", "Yay")

The correct way to use Not is:

If Not(1 = 2) Then MsgBox(4096, "", "Yay")

The rest of the tests are unbalanced as follows:

> - No assignment is performed, ever

>= - One assignment is performed

< - Assignment is performed every pass but the last pass

<= - Assignment is performed every pass

Running the tests to minimize the amount of asignments occurring, =, >=, <=, <, > all run in the 13 - 14 second range. Not() ran at over 19, but it assigned $x every time but one so it's result is invalid in relation to the others. >= and <= both assigned only once each. (Note: It's impossible to use this particular test to compare both = and Not because one is always going to perform assignment all but one time while the other will only assign once.)

Edited January 23, 2004 by Valik

[MattNis]

> and >= are still the quicker of all....though not by much

and the times I got changed a negligeable amount from the first test I posted

expandcollapse popup

$start = TimerStart()

For $i = 0 To 262144
    if $i = $i-1 then $x=0
Next

$equal = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i >= $i+1 then $x=0
Next

$ge = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i <= $i-1 then $x=0
Next

$le = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if NOT($i = $i) then $x=0
Next

$ne = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i < $i-1 then $x=0
Next

$less = TimerStop($start) / 1000


$start = TimerStart()

For $i = 0 To 262144
    if $i > $i+1 then $x=0
Next

$greater = TimerStop($start) / 1000

MsgBox(4096, "Execution time:", "=" & $equal & @LF & ">=" & $ge & @LF & "<=" & $le & @LF & "!=" & $ne & @LF & "<" & $less & @LF & ">" & $greater)

Edited January 23, 2004 by MattNis

[MattNis]

if 1 NOT = 2 then MsgBox(0, "","1 Wrong")

if NOT(1 = 2) then MsgBox(0, "","2 Wrong")

you were right about the above

Edited January 23, 2004 by MattNis

[Manus-Magnus]

peace. Tx you guy i tested, you test saying > or < are the fastest logicial if it's bit calculated, and so, tx you so much.

simply the idea of USE timer start/stop to test and optimize some points is the final answer i think.

mm