Eval Function

[tozeina]

Can any one help in this please.
I'm using eval function in JavaScript, But when the eval method return
a big big number the result will be a number with "E"
for example :
Eval(1000000000 000000000000) will result 1e+21
I need to get the number as it is . can i ??

Thanks in advance

[Baconbutty]

Re: Eval Function

Generally no.

Javascript numbers have limited precision (i.e. they can only contain a
finite number of digits), following the IEEE standards. See:-

http://en.wikipedia.org/wiki/IEEE_floating-point_standard

You will need to research arbitrary precision mathematics if you really
need greater precision.

[Lasse Reichstein Nielsen]

Re: Eval Function

"tozeina" <tozeina@gmail. com> writes:
[color=blue]
> I'm using eval function in JavaScript,[/color]

Probably a bad idea.
<URL:http://jibbering.com/faq/#FAQ4_40>
[color=blue]
>But when the eval method return
> a big big number the result will be a number with "E"
> for example :
> Eval(1000000000 000000000000) will result 1e+21[/color]

That would be the default string representation of that number for
your browser. The notation "1e+21" means 1 * 10^21, i.e., 1 with
21 zeroes after it, which is exactly the number you entered.

You should also be aware, that numbers that big can't all be represented
exactly. E.g., (1e+21 == (1e+21 + 1)) gives true, because the 64 bit
floating point numbers used by Javascript does not have the resolution
to represent (1e+21 + 1).
[color=blue]
> I need to get the number as it is . can i ??[/color]

You can compute your own string representation of the number.
Maybe something like:
---
function numberToString( number, base) {
base = base || 10;
var res = [];
while (number > 0) {
var digit = number % base;
res.push((digit < 10) ? digit : String.fromChar Code(digit - 10 + 97));
number = (number - digit) / base;
}
return res.reverse().j oin("");
}
---
Call it as:
numberToString( 1e+21, 10)
Make sure base is an integer between 2 and 36!

/L
--
Lasse Reichstein Nielsen - lrn@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleD OM.html>
'Faith without judgement merely degrades the spirit divine.'

[Danny]

Re: Eval Function



The number should come out as is by default, it should't use the Euler's
format, I think the issue is in your using eval(), eval() is outputting
such, instead, skip eval() altogether.


Danny
--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

[Dr John Stockton]

Re: Eval Function

JRS: In article <1123677937.150 597.85710@f14g2 000cwb.googlegr oups.com>,
dated Wed, 10 Aug 2005 05:45:37, seen in news:comp.lang. javascript,
tozeina <tozeina@gmail. com> posted :[color=blue]
>Can any one help in this please.
>I'm using eval function in JavaScript, But when the eval method return
>a big big number the result will be a number with "E"
>for example :
>Eval(100000000 0000000000000) will result 1e+21
>I need to get the number as it is . can i ??[/color]

No doubt you should not in fact be using eval - see newsgroup FAQ 4.40.

In javascript, Numbers are stored as IEEE Doubles, a binary floating-
point format. If you want to see that, which you don't, consider
<URL:http://www.merlyn.demo n.co.uk/js-misc0.htm#IEEE> .

If you really do need to express a large number in fixed-point, you will
need to accept rounding errors (though it may be possible to mask the
obvious ones) - see BigStrOfMN in
<URL:http://www.merlyn.demo n.co.uk/js-round.htm#CAI>.

Alternatively, if you want results accurate past one part in about 1e15,
you can implement your own arithmetic using arrays of digits to
represent numbers. I've done it, for Pascal/Delphi integer work, in
<URL:http://www.merlyn.demo n.co.uk/programs/longcalc.pas>.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
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