Auto it problem with @error and Do...Until loops

[RichardR]

Hello. In my script I find that using the following code runs eternally because @error  is always 0 even when it shouldn't be.

Func test()
    Local $t = 90, $c = 0, $ps
    Do
        $ps = PixelSearch(570, $t, 590, $t + 15, 0xCCD0D6, 15, 1, $Hwnd)
        MsgBox(0, "test", IsArray($ps) & ", " & "error = " & @error, 0, $Hwnd)
        If (@error = 0) Then
            $t += 25
            $c += 1
        EndIf
        Sleep(100)
        MsgBox(0, "test", "error = " & @error, 0, $eveHwnd)
    Until @error = 1
    Return $c
EndFunc

 

The message box shows me that PixelSearch found something 4 times; but after that, isArray returns false but @error is also 0. This doesn't happen with a While...Wend loop.

Any thoughts?

[water]

Welcome to AutoIt and the forum!

MsgBox overwrites @error. So you are checking the value of @error returned by MsgBox not by Pixelsearch.

[Melba23]

RichardR,

Welcome to the AutoIt forums.

No bug - AutoIt resets @error each time you call a function - so your MsgBox call overwrites the return from the Pixelsearch line above it. Save the value of @error into a variable before calling the MsgBox and then use that variable in the comparison.

M23

P.S Hi water!

Edited December 24, 2018 by Melba23

[ajag]

as water says.

Look at this:

SetError (11)
MsgBox(0, '', '@error = '  & @error)
MsgBox(0, '', '@error = '  & @error)

 

[pixelsearch]

@ajag : I'll always remember the following one, very surprising when it happens to you the 1st time

#include <MsgBoxConstants.au3>
SetError (11)
MsgBox(BitOr($MB_ICONWARNING, $MB_TOPMOST), "Surprise !", "@error = "  & @error)

@RichardR : welcome !
The help file is your best friend, just have a look at the SetError topic, all explanations are there.
Good luck for your future scripts

By the way, you wrote that "The message box shows me that PixelSearch found something 4 times..."
It's true, i always check 4 times to make sure

Edited December 24, 2018 by pixelsearch

[RichardR]

Thanks for explaining how @error works. I have looked at the help file many times. The MsgBox function didn't mention anything about setting the @error so I thought, at first, it had nothing to do with it. After reading about SetError, it seems that entering a function resets @error to 0. It also mentioned I should try storing @error in a variable which I already did. Thanks.