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Re: NSNumber stringValue
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Re: NSNumber stringValue


  • Subject: Re: NSNumber stringValue
  • From: Ben Haller <email@hidden>
  • Date: Sat, 12 Dec 2009 12:32:42 -0500

You should not compare floating point numbers for equality in most cases. This is true of any language on any platform.

Indeed, some floating-point numbers (such as the one represented by the integer 0x7fc00000) will compare as not equal to themselves:

I think what the OP really wanted to know (and I'm interested in the answer too) is whether going out to the stringValue and back to the doubleValue is guaranteed to yield a float that is bitwise identical to the original float, or whether there is "drift" in the least significant bit or two due to the changes in representation. Anyway, even if that's not the OP meant, that's what I'd like to ask. :->


Ben Haller
Stick Software

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