Re: extracting the mantissa for a NSDecimal
Re: extracting the mantissa for a NSDecimal
- Subject: Re: extracting the mantissa for a NSDecimal
- From: Tom Bernard <email@hidden>
- Date: Fri, 20 Nov 2009 04:43:19 -0700
- Thread-topic: extracting the mantissa for a NSDecimal
Hello Olivier,
I am working with NSDecimals and ran across your 7 year old post in
Cocoa-dev. Did you ever get an answer to your mantissa question? The
archives do not show a response to the thread.
Btw, did you consider NSData's
+dataWithBytes:length:
method?
NSData *anNSDecimalAsData = [NSData dataWithBytes:&anNSDecimal
length:sizeof(NSDecimal)];
gives you an NSData object suitable for an NSDictionary without having to
muck around with NSDecimal's private fields.
++ Tom
Tom Bernard
email@hidden
> --__--__--
>
> Message: 11
> Date: Tue, 29 Oct 2002 12:37:35 -0600
> Subject: extracting the mantissa for a NSDecimal
> From: Olivier <...>
> To: cocoa apple <...>
>
> i'm trying to save an NSDecimal in a dictionary.
>
> I study the NSDecimal structure and decided that all i really need to
> save are:
> _exponent, _isNegative and _mantissa field
>
> i'm trying to get the mantissa field, i want to store it as a NSNumber
> in my dictionary.
>
> the length field of the NSDecimal tells how many short of the mantissa
> are relevant
>
> so i'm building my data this way:
>
> NSMutableData *theNumberData = [NSMutableData
> dataWithLength:16];
> for (i = 0; i < valueOfObject._length; i++)
> {
> [theNumberData replaceBytesInRange: NSMakeRange(16 -
> (i+1) * 2, 2)
> withBytes:
> &valueOfObject._mantissa[i]];
>
> }
>
> so that the relevant field are put in the data object starting from the
> end of the object (most significant bytes first)
>
> then start the problem, converting it to an NSNumber i tried:
>
> const char *theNumberPtr = [theNumberData bytes];
> [NSNumber numberWithUnsignedLongLong: *theNumberPtr]
> [NSNumber numberWithUnsignedLongLong: theNumberPtr[0]]
> [NSNumber numberWithUnsignedLongLong: &theNumberPtr]
>
> without any success.
>
> Any idea of how to get that mantissa in a NSNumber?
>
> Olivier
>
> --__--__--
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