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parseInt "problem" 2

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LFI

LFI

Programmer
Apr 27, 1999
1,996
US
Here's an odd one. It took me a while to find my bug because I didn't even think about THIS:

parseInt('08') returns 0 (not 8, as I would expect). Can anyone figure why this might be? I can't begin to imagine!

--Dave

P.S., try it for yourself!
Code: 
<html>
<head>
<script>
alert(parseInt('08'));
</script>
</head>
</html>
 
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'z8' -> NaN
' 8' -> 8
'\n8' -> 8
'89z' -> 89
'0z' -> 0
'08' -> 0

Cute. I am thinking numbers do not have leading zeros according to some deep mathematical definition somewhere.

We become accustomed to seeing 08/25/05 and thinking that means month 8. But maybe it really means code 08 for August.

When we count, we count 1, 2, 3; not 01, 02, 03. And if you wanted to, how would you decide whether to count 01, 02, 03; or 001, 002, 003; or 0001, 0002, 0003. Or which comes first 0001 or 000001? So maybe those latter are not numbers. In which case parseInt('08') is correct.

But I feel your pain. '08' sure looks like 8 to me.

Thanks.


 
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LookingForInfo,

If you tell it what your "base" is it will work more like expected.

Code: 
var x = '08';
alert(parseInt(x, 10));


Thanks,
 
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Numbers that start with 0 are translated as octal in Javascript (and numbers starting with 0x are hexadecimal). This means that 08 and 09 are impossible, and requires defining the base as 10.

Lee
 
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Well now THAT makes sense! Thanks, Lee!

--Dave
 
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Lrnmore,

As many times as I've seen that advice, I have NEVER yielded to it. Now I have found a real-life instance in which I would have benefited from it! Thanks for the reminder I'm a believer now! :)

--Dave
 
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Dave,

Well you'd think they would call us up here at Tek-Tips and ask how things should be done. ;)

For instance why, and I'm guessing some folks here could explain the reasoning behind this, would this ever "parse" as an integer.

Code: 
var x = "089this is not an integer";
alert(parseInt(x, 10));

Logically, I'd expect that to return NaN.
But that's just me I suppose.

Thanks,
Mark
 
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