[VB6] Exit Application

[eccofresh]

Hi,

I have written a VB6 application, and want to exit it if a certain condition happens. All my code gets called from the Form_load event and the form it self is never shown. I tryed using "unload me" or "unload form1" but that didnt work.

So what command would I use in VB6 to close the application?

thx in advance!

[zeta]

You should be able to use "Unload Me" in Form_Load... but you could use "End"...

[James Rose]

Actually a Form Unload or "End" command during the Load event can cause problems and/or simply not work so...

declare a module level variable

Private mbUnload as Boolean

Sub Form_Load

If Conditions_Met Then

mbUnload = True

End if

End Sub

Sub Form_Activate

If mbUnload = True Then

Unload Me

End If

End Sub

[nvme]

ive never had End not work before, but i would assume doing an Exit Sub in the form_load should theoretically work

[eccofresh]

sweet, it worked when I put the unload me in the Form_Load. Why doesnt it work when I put it in a different sub though?

I was reading something about End before, but it sounded kinda negative and that it shouldnt be used... ?

I actually solved my problem too by using a module instead of a form and by using the exit sub command in the last sub that gets called.

still thx guys:yes:!

[zeta]

Well, I don't typically work with VB much, but the comparison I have heard is that using End is like stopping a car by running it into a brick wall--why do that when you could just use the brakes?

[James Rose]

I have been a professional VB dev since 1994.

"End" is not a bad keyword, in fact it is a good thing. Doing a simple Unload MAY not completely release all objects in use by your application. End releases all variables and objects. See: MSDN

[zeta]

It seems from MSDN that the preferred method is to just unload all the forms though? When that happens, the application will exit, so memory will be freed and open files closed, regardless of whether or not End is called.

[James Rose]

<sigh> I just know I am going to regret posting this but...

"End" is the proper way to completely stop an application becuase, often, application are more than just Forms, and often do not include Forms at all. Simply doing an Unload on all Forms will not nessasarily destroy all objects (classes, references, etc).

Although Unload is not bad, it is not complete.

(please take this message as it was intended, to inform, not inflame)

Sincerely,

James Rose

New York City

[zeta]

  jameswjrose said:

Simply doing an Unload on all Forms will not nessasarily destroy all objects (classes, references, etc).

586138573[/snapback]

Err, why would you regret posting it? I'm just curious--to the best of my understanding, if you unload all the forms, won't the application be closed anyway by the system? I understand that a VB app is often more than just forms. But, according to MSDN, in the documentation for the End statement:

  Quote

For normal termination of a Visual Basic program, you should unload all forms. Your program closes as soon as there are no other programs holding references to objects created from your public class modules and no code executing.

The other resources (classes, references, file handles, etc) should be reclaimed by the OS once your application terminates, right?

[James Rose]

See, that's the thing, the Garbage collector in VB6 runs when a function/procedure ends (as opposed to .Net which runs at rather random intervals, or you can call it specifically, but this is another issue)

Say you had an app with one Form and one Class. Say the class is created when you load the form. The class SHOULD be destroyed when you unload the form. However this is not always the case. The End command makes sure ALL references are destroyed. The reason for this importance is that if your app is started again, is is possible (however unlikely) that the previous values from the original class will still be in memory.

In fact, we had a VERY similar situation about class destruction in our app just this month. (I have NO idea how the values were not being cleared but....)

End will guarentee that all memory will be cleared.