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Trouble with parsing text to float…

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Sep 18.2007

I’m trying to parse some text inputs into floats and then add them together, but it isn’t working for some reason….

35.87 and 35.86 are the inputs however when added together they give 71.72999999999999 which makes no sense, is there some weird rounding thing I’m not understanding? But there wouldn’t even be a need for rounding, they add up perfectly to 71.73.

bk13amt=parseFloat(bk13amt.value);
bk7amt=parseFloat(bk7amt.value);
currentnum = bk13amt + bk7amt;

Anyone have any ideas?

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JavaScript

3 Comments(s) ↴

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@KravvitzSep 19.2007 — The rounding error is caused by converting between decimal and binary.

[url=http://forums.devshed.com/showpost.php?p=1498326&postcount=3]Kor explains a bit more here.[/url]
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@xvszeroauthorSep 19.2007 — Yeah tofixed seems to work, but I'm still a bit nervous.
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@KravvitzSep 19.2007 — Nervous? Why?

//This snippet adds the method in older browsers that don't support it natively:
if(!0.1.toFixed && Number.prototype){
// for IE versions older than 5.5 and Netscape 4.x.
Number.prototype.toFixed=function(d){
d=(d&&d>1?((d<=20)?Math.floor(d):20):0);
var n=this,f=Math.pow(10,d);
n=((Math.round(n*f)/f)+Math.pow(10,-(d+1)))+'';
return n.substring(0,n.indexOf('.')+(d==0?0:d+1));
}
}
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