Cancelling Routines

[Denk]

I have created a program which carries out quite lengthy calculations. I want to add an option to cancel the calculation at any point.<br><br>I added a Command Button to act as a Cancel button, but when this button is clicked the calculation routines continue.<br><br>How do I stop the calculation routines after the Cancel button has been pressed?

 

[Alt255]

If you are using an iterative loop to perform the calculations you could perform a DoEvents inside the loop and immediately check the value of a variable set in the button's Click event.<br><br>If CancelThis = True then Exit Sub.<br><br>The DoEvents will slow down your calculations <i>considerably</i> but there aren't a lot of ways for a user to interrupt a loop. <p> <br><a href=mailto:InterruptX@excite.com>InterruptX@excite.com</a><br><a href=

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Contingency Implementation</a><br>Send me suggestions or comments on my current software project.

 

[Jerrycurl]

Depending on how many iterations are in the loop, you could increment a counter variable and only call DoEvents every 10 or 20 (or whatever) iterations.&nbsp;&nbsp;

 

[Jerryls]

Here is a trick for DoEvents.<br>Notice the &quot;stop&quot; button does not even have<br>to be in your loop.<br>1-Put a Boolean in your Declarations.<br>2-Dim a &quot;throw-away&quot; variable before<br>&nbsp;&nbsp;entering your calculations.<br>3-Increment the variable in the loop<br>&nbsp;&nbsp;and use MOD to check it. This will<br>&nbsp;&nbsp;increase the speed of your loop, because<br>&nbsp;&nbsp;DoEvents will be triggered less often.<br><br>'Declarations Section<br>Dim Quit As Boolean<br><br>'Stop Button Code<br>Private Sub cmdStop_Click()<br>&nbsp;Quit=True<br>End Sub<br><br>'Code for Calculations<br>Private Sub Calculate()<br>Quit=False&nbsp;&nbsp;'Set Quit=False each time<br>Dim t As long<br>Start loop&nbsp;&nbsp;'Calculations Start<br>'code<br>t=t+1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'Increment t<br>If t MOD 100 Then DoEvents&nbsp;&nbsp;'Let VB do other things.<br>If Quit Then Exit Sub&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'Exit if Stop Button Clicked<br>if t&gt;20000 then t=0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'reset t now and then<br>'code<br>'code<br>Finish loop<br>End Sub<br>