On Apr 14, 2006, at 7:10 PM, Mark O'Neill wrote:
Hi All,
I've noticed that many snippets of code I've seen use something like:
for i = UBound(MyArray) DownTo 0
...
next
instead of
for i = 0 to UBound(MyArray)
...
next
Now, aside from the obvious that DownTo is in reverse order are
there any gains in using DownTo?
Code correctness is sometimes a gain. Suppose you want to loop
through an array and remove some elements. Using downto makes it
much easier.
For i as Integer = UBound(theArray) downto 0
If theArray(i) = "foo" then
theArray.Remove i
End if
Next
You can't implement this with a loop in the other direction unless
you modify i in the loop, which is considered bad style. Instead you
would need to use a While loop --
dim i as Integer = 0
While i <= UBound(theArray)
If theArray(i) = "foo" then
theArray.Remove i
Else
i = i + 1
End if
Wend
Charles Yeomans
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