calculation error

[chun914]

I have some numbers like below and the final $temp amount should be 450 exact but the calculation ended up with 450.00000000001..

i have no idea what's going wrong ?

$p = 4592.05
$1 = 679.41
$2 = 661.31
$3 = 660.04
$4 = 648.06
$5 = 963.85
$6 = 529.38

$childsum = 0

$childsum += $1
msgbox(0,"",$childsum)
$childsum += $2
msgbox(0,"",$childsum)
$childsum += $3
msgbox(0,"",$childsum)
$childsum += $4
msgbox(0,"",$childsum)
$childsum += $5
msgbox(0,"",$childsum)
$childsum += $6
msgbox(0,"",$childsum)

$temp = $p -$childsum
msgbox(0,"",$temp)

[AdamUL]

This is due to floating point arithmetic. Since none of your numbers has a precision greater than two decimal places, use the following.  

Round($temp, 2)

[chun914]

i have to check if the sum + 450 = $p.......

if $childsum + 450 = $p Then
   msgbox(0,"","so something")
Else        
   msgbox(0,"","oops")
EndIf

Edited May 31, 2013 by chun914

[AdamUL]

Then use the following after your arithmetic.

$childsum = Round($childsum, 2)

Edited May 31, 2013 by AdamUL

[Melba23]

chun914,

As all the amounts have 2 decimal places I would convert all of them to integers (i.e. multiply them by 100) so that I could use integer arithmetic to sum them. Then I would divide by 100 and use Round when I wanted the total back in 2 decimal place format.

M23

[chun914]

thanks.. M23,

finally get it done by *100 and compare using int($a) = int($