Understand "And"

[Hawk]

Topic name should be [understanding "And"], can't I change it?

I heard that in other languages like C it's in general like this (or only with code optimization, i don't know), that only so many conditions connected with "And" are checked, until one condition is not met.

Example:

If $a = 1 And $b = 2 And $c = 3 And $d = 5 Then
    ...
EndIf

Are all 4 variables checked here always? Or only until one condition is not true? If, then from which side? From left to right (first $a, then $b...) or from right to left (first $d, then $c...)?

And can I tell AutoIT to optimize it on demand?

If I am only checking some variables, I want to only check them until one condition is not true to save processing time.

But in another case where I call a function that also changes variables, I want to check ALL conditions so each function is also processed!

Example:

If WinMove("win1", "", 100, 100) And WinMove("win2", "", 500, 500) Then
    ...
EndIf

Edited March 6, 2012 by Hawk

[Melba23]

Hawk,

As I understand it AutoIt evaluates multiple AND expressions left to right until one of them returns False. OR works similarly and the evaluation ends as soon as an expression returns True. The order is as set by you when the condition is coded and is not "optimizable".

If you want to run all your functions then I suggest you run them first assigning the return value to a variable and then check those variables in the multiple AND statement like this:

$Win_1 = WinMove("win1", "", 100, 100)
$Win_2= WinMove("win2", "", 500, 500)

If $Win1 And $Win2 Then
    ...
EndIf

M23

[Hawk]

Thanks once again Melba23

I guess in a switch-case-statement values are checked from up to down?

Switch $a
    Case 3
        ...
    Case 4
        ...
EndSwitch

So $a is first checked for 3, and only for 4 if it is not 3, right?

And a little bit offtopic, but here is a small example:

Global $a = 4
Select
    Case $a = 4
        MsgBox(0, "", "4")
    Case $a = 5
        MsgBox(0, "", "5")
    Case Mod($a, 4) = 0
        MsgBox(0, "", "var % 4 = 0")
EndSelect
Exit 0

How would I let a select statement check for all cases? Here the script only shows one messagebox, where it should really show two. If $a is 4, the second messagebox will never pop up.

Can this be done?

[JohnOne]

If the expression is true the following statements up to the next Case or EndSelect statement are executed. If more than one of the Case statements are true, only the first one is executed.

EDIT:

Try ContinueCase after the conditional statements.

Edited March 6, 2012 by JohnOne

[Melba23]

Hawk,

Again with the proviso that this is only my understanding, you are correct about Switch and Select structures working from top to bottom. And they only action a single Case - so if you want to check the Mod value you will need another structure:

Global $a = 4
Switch $a
    Case 4
        MsgBox(0, "", "4")
    Case 5
        MsgBox(0, "", "5")
EndSwitch
Switch Mod($a, 4)
    Case  0
        MsgBox(0, "", "var % 4 = 0")
EndSwitch
Exit 0

M23

Edit:

JohnOne,

ContinueCase just runs the code for the next Case, it does not evaluate the condition. It can be quite useful when exiting - like this:

Switch $iVar
    ; Save and exit
    Case 1
        ; Do saving of vars etc here
        ContinueCase
    ; Exit directly
    Case 0
        ; Clean up code goes here and is run in both cases
        Exit
EndSwitch

Edited March 6, 2012 by Melba23

[JohnQSmith]

ContinueCase just runs the code for the next Case, it does not evaluate the condition.

That is interesting. I did not know this. I thought it was removing the "C++ break" statement from the case allowing the switch to continue parsing instead of breaking out. I'm going to have to revisit my code.

[Hawk]

I see.. I thought it can be done somehow in one 'select'. But luckily I won't need that often. Thanks for the answers!