Problem with Number(), parseFloat(), eval()

@eerdemMar 02.2004

Does anybody have any idea why this code wouldn’t give me the correct value for the variable “test”:

var test = Number(5) + Number(12.4) + Number(0) + Number(0.4) + Number(0);

I expect the result to be 17.8, instead I get 17.799999999999997 If I use eval() or parseFloat() instead of Number() the result is the same… I don’t want to round up the number.

I’m really curious why the test code above wouldn’t give me the correct result, and what I should do to get the correct result. Thanks!!!

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JavaScript

@fredmvMar 02.2004 — #[i]Originally posted by eerdem [/i]

[B]var test = [color=blue]([/color]Number(5) + Number(12.4) + Number(0) + Number(0.4) + Number(0)[color=blue]).toFixed(1)[/color];[/B][/QUOTE]See: http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/number.html#1200964.

@eerdemauthorMar 02.2004 — #Thanks fredmv, but toFixed() method is essentially rounding up the number. I don't want to do that. It's weird that for the example I posted I can't get the correct result but for many other numbers it works fine.

A simpler example where again can't get the correct result is this:

var test = Number(5.4) + Number(3.2); alert(test);

Try it... result is NOT 8.6!!!!

@oleragMar 02.2004 — #There was a good example as to the why but I can't find it

as yet - I'll keep looking. But to resolve the problem, you

can issue the toFixed() function, with the desired amount of

decimals.

[code=php]
 <script type="text/javascript">
 function execute() {
 var numb = parseFloat(5+12.4+.4).toFixed(1);
 alert("Result: " + numb);
 }
 </script>
 [/code]

fred is too fast for me...

In this [URL=http://forums.webdeveloper.com/showthread.php?s=&threadid=11743&highlight=decimals]thread[/URL] [b] lavalamp[/b] provides a

lengthy solution but I think toFixed() is alot easier. I'm still

looking - there's a thread in here somewhere that provides

an explanation as to why this occurs.

The closest explanation I can find is from [b]pittimann[/b] as to

why JS sometimes provides an erroneous floating point

value and is [URL=http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/number.html#1207032]here[/URL].

Problem with Number(), parseFloat(), eval()

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