[SOLVED] problem understanding this while loop

[crouzilles]

Hi all.

i am new to autoit and to programming in general.

I am reading the help file a lot and some example scripts people have been sharing in the "Example Scripts" part of this forum.

Very often I come across something like this:

While 1
    Sleep(100)
WEnd

This example can be seen in the script at this

What I don't understand is that this while loop should be infinite and the program would always sleep and not do anything else.

The program does work, so I am obviously not understanding what the while loop does, if anyone here could explain this to me, I would be delighted.

I hope you don't think I am being daft or anything, I am really stumped by this.

Thank you

Crouzilles

Edited January 21, 2011 by crouzilles

[guinness]

Basically your Example above will continue to loop until 1 becomes something else, now as you have pointed out this will loop will continue continuously, because nothing in that loop will change 1 to something different. Normally to Exit a loop like this users use ExitLoop or check out this Example...

Global $One = 1
While $One = 1
    Sleep(2000)
    MsgBox(0,"Change the Variable", "Now we will change $One to something else other than 1")
    $One = 10
WEnd
MsgBox(0,"We Ended the Loop", "See...")

Edit: And that Example is often used in GUIOnEventMode()

Edited January 21, 2011 by guinness

[crouzilles]

Basically your Example above will continue to loop until 1 becomes something else, now as you have pointed out this will loop will continue continuously, because nothing in that loop will change 1 to something different. Normally to Exit a loop like this users use ExitLoop or check out this Example...

Global $One = 1
While $One = 1
    Sleep(2000)
    MsgBox(0,"Change the Variable", "Now we will change $One to something else other than 1")
    $One = 10
WEnd
MsgBox(0,"We Ended the Loop", "See...")

but the while loop uses the value 1 and not a variable which can have its value changed. so how does the program get out of this while loop?

Thank you

Crouzilles

[guinness]

Check out ExitLoop in the Help File! This will give you a good Example of exiting a loop such as this.

Edited January 21, 2011 by guinness

[Melba23]

crouzilles,

A script needs to be kept "alive" or it just ends. The way to keep it alive is to use an infinite loop.

There are 2 modes in AutoIt - OnEvent and MessageLoop - which you use decides how you contruct the loop.

In OnEvent mode, the script waits for events and then runs the function associated to these events by GUISetOnEvent or GUICtrlSetOnEvent. So to keep the script alive you need an infinite idle loop - which must include a Sleep statement to avoid overloading the CPU. You finally exit the script via one of the functions.

In MessageLoop mode you again stay in a loop, but this time you look for the messages passed when controls are activated bu using GUIGetMsg - you also do not need a Sleep statement as GUIGetMsg provides its own idle time to the CPU. You exit the script either by using ExitLoop to leave the loop or just a plain Exit to quit the script.

Does that help? Please ask again if you still have questions.

M23

[crouzilles]

crouzilles,

A script needs to be kept "alive" or it just ends. The way to keep it alive is to use an infinite loop.

There are 2 modes in AutoIt - OnEvent and MessageLoop - which you use decides how you contruct the loop.

In OnEvent mode, the script waits for events and then runs the function associated to these events by GUISetOnEvent or GUICtrlSetOnEvent. So to keep the script alive you need an infinite idle loop - which must include a Sleep statement to avoid overloading the CPU. You finally exit the script via one of the functions.

In MessageLoop mode you again stay in a loop, but this time you look for the messages passed when controls are activated bu using GUIGetMsg - you also do not need a Sleep statement as GUIGetMsg provides its own idle time to the CPU. You exit the script either by using ExitLoop to leave the loop or just a plain Exit to quit the script.

Does that help? Please ask again if you still have questions.

M23

Melba23, thank you very much for the explaination. The fog of ignorance has suddenly been lifted off my eyes, on this topic at least

guinness, thank you for your contribution, I think we may have been talking about a slightly different problem, but any help is very much appreciated.

Regards

Crouzilles

[guinness]

guinness, thank you for your contribution, I think we may have been talking about a slightly different problem, but any help is very much appreciated.

OK I thought you were confused about infinite Loops?! Sorry about that Edited January 21, 2011 by guinness