Exiting a For ... Next Loop Early

If you use For ... Next loops in your macro programming (who doesn't?), then you should know that they can take a great deal of time. You can minimize this by only checking what you need. For instance, consider the following code, which checks an array to see if a value exists. If it doesn't, then it adds the value to the end of the array. If it does, then the value is not added.

AddIt = False
For J = 1 to NumEntries
    If NumValues(J) = ToAdd Then AddIt = True
Next J
If AddIt Then
    NumEntries = NumEntries + 1
    NumValues(NumEntries) = ToAdd
End If

This works great, but if the array gets large, you can end up going through the For ... Next loop quite a few times. Now consider the following code, which accomplishes the same task, but dumps out of the For ... Next loop early if a match is detected.

AddIt = False
For J = 1 to NumEntries
    If NumValues(J) = ToAdd Then
        AddIt = True
        Exit For
    End If
Next J
If AddIt Then
    NumEntries = NumEntries + 1
    NumValues(NumEntries) = ToAdd
End If

Now if a match is found early on in the loop, all the rest of the iterations are skipped because the Exit For statement is encountered and the loop is basically exited right away. The result is a faster running macro.