iPhone SDK NSUserDefaults not saving correct values -

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I can use some help. There are consecutive lines of code here: 

  NSLog (@ "StartTimer (after a few frustrating days of testing and error), I have NSUserDefaults writing results incompatible.  
 ): End time defaults:% f \ n ", [Default floatio: kentthemake]); NSLog (@ "Start Timer (New: End Time:% f \ n", Endime); [Default Set Flame: Endime Farke: Kandtmeke]; [Synchronize default]; NSLog (@ "Start Timer (): Archived Endtime:% F \ n", [Default Floatio: KandTameKey]);

kEndTimeKey is a constant string.

If I can see the current value log for the key, then I think the value I want to store is logged, synchronize, then read the stored value again seems easy for me, But here's the Debugger output: 

  2009-07-22 22: 05: 43.263 TimerTest3 [1584: 207] startTimer (): End time defaults: .0,00,000 2009-07- 22 22: 05: 43.266 TimerTest3 [1584: 207] startTimer (): New End Time: 270018630.9 16571 2009-07-22 22: 05: 43.287 TimerTest3 [1584: 207] startTimer (): Archived EndTimeKey: 27,00, 18,624.00 000

I see cash original values ​​read off 6 seconds 0, intended value ending in 571, and value.

I'm not sure where the new default came from. any idea? I get the same behavior on the device and on the simulator.

thanksbrad

How are you setting up the endime is a double ? I'm relatively certain that this is not an NSUserDefaults issue, but there is a floating point math problem.

270018630.916571 is 16 decimal digits, which takes ~ 48 bit of data to store Mantissa. A floating point is 32 bits, but its 1 bit is a signal bit, 8 bits of exponents and 23 bits of mantas. This means that the value you are looking at can be larger than the float, and there is the possibility of losing some precision even if you shorten it in 270018630, which is still 28 bit consens , Which means that it has to pay bigger increments than the whole number.

Floating point numbers do not express you magically, with the same number of bits, large numbers compared to ints, changing the gap between large numbers of numbers and using metadata (exponent) To make it the ability to track. How they work in Wikipedia, it's a decent one.


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