Overflow

[TedMartin]

I have some code that is puzzling me.

Dim iCycle as Long
Dim iStep as Integer

iStep = 10

more code ...

If iCycle >= 10 * 60 * 1000 / iStep then
'Do something
end if

I get a Error 6 overflow on the IF line of code.

If iCycle >= 10 * 60 * (1000 / iStep) then

I don't understand as 10*60*1000 = 600,000 which is well within the Long range.

Anyt thoughts would be welcome.


However it does not erro if the line of code is

 

[boblarson]

Looks like you got cut off there in mid sentence.

As for the overflow, try changing iStep to a LONG instead of Integer and see what happens. You also have to take into account zeroes if iStep is a zero it can't be used as a divisor.

 

[MarkK]

The problem here is that VBA interprets each of these numbers as integers

10 * 60 * 1000

and so tries to use integers to do the math, but the biggest integer is 32767. For example, type

? 32767 + 1

in the immediate window and you'll get an overflow error. If you explicity indicate a long for one of the numbers the problem goes away, because VBA uses Longs to do the math ...

10& * 60 * 1000  [COLOR="Green"]'the ampersand declares the number as a long[/COLOR]
clng(10) * 60 * 1000  [COLOR="Green"]'or use the CLng() function[/COLOR]

 

[ted.martin]

Got it - thanks. I can rest east now I understand why.

 

[ted.martin]

Sorry Bob; my post should have read:

I have some code that is puzzling me.

Dim iCycle as Long
Dim iStep as Integer

iStep = 10

more code ...

If iCycle >= 10 * 60 * 1000 / iStep then
'Do something
end if

I get a Error 6 overflow on the IF line of code.


However it does not error if the line of code is:

If iCycle >= 10 * 60 * (1000 / iStep) then

I don't understand as 10*60*1000 = 600,000 which is well within the Long range.

Any thoughts would be welcome.