====== QTIPS - FOR/NEXT variables=====

^Published By^Date^Version^Knowledge Level^Keywords^
|Sprezzatura Ltd|01 JUN 1992|2.12+|EXPERT|FOR, NEXT, STEP|

Tony McDowell writes - "The documentation (page N4.73) states that "start",
"end" and "step" must be integers. A little experimentation might suggest
that in fact any decimal fractions can be used for these variables. Don't be
fooled. If STEP is a decimal fraction then anomalous results can occur.
Specifically, it seems that the "even-ness" of the bound and step variables
is critical. My tests show that if step and the lower and upper bounds are
"even" decimal fractions then the FOR/NEXT loop will incorrectly terminate
when step is equal to "end" rather than when it exceeds "end" (or underflows
if step is negative)."

<code>
     * This one is bad - it won't hit -2.0
     A = 2 ; B = -2
     For I = A To B Step -0.2 ; Call Msg("I = " : I) ; Next

     * This one is OK
     A = 1 ; B = -1
     For I = A To B Step -0.2 ; Call Msg("I = " : I) ; Next

     * This one OK
     A = 2 ; B = 4
     For I = A To B Step -0.5 ; Call Msg("I = " : I) ; Next

     * This one is bad - it won't hit 4.0
     A = 2 ; B = 4
     For I = A To B Step -0.4 ; Call Msg("I = " : I) ; Next
</code>

* NB Version 2.12 MSG used above!


(Volume 4, Issue 2, Page 5)