CODEWITHSUNDEEP
objective-ccocoacocoa-touch
Mike Reedell
Mike Reedell

Reputation: 1587

Convert between a C double and Cocoa's NSDecimalNumber?

I'm converting an algorithm I wrote in Java to Objective-C. In java the BigDecimal class handles base-10 numbers and can take the primitive double as a constructor arg. In Cocoa's NSDecimalNumber class, however, there is no direct way to construct an instance using a primitive double.

Currently I'm using this (smelly) hack:

    [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%1.38f", number]];

Is there a better way?

Upvotes: 5

Views: 5098

Answers (5)

Futurist
Futurist

Reputation: 19

In other posts I'm finding info that using the NSNumber methods with NSDecimalNumber either will return NSNumber, or will return NSDecimalNumber but that's not what the spec says it should so it may be considered a bug and change in the future. Er something like that.

Upvotes: 0

Echilon
Echilon

Reputation: 10244

You can also use [[NSDecimalNumber alloc] initWithDouble:(double)], it's just not as obvious.

Upvotes: 5

skylerl
skylerl

Reputation: 4180

I've found the way to get this to work, and to dismiss the warning is like this.

    NSNumber *temp = [NSNumber numberWithDouble:self.hourlyRate];
    myDecimal = [NSDecimalNumber decimalNumberWithDecimal:[temp decimalValue]];

It gets rid of the warning, albeit being two lines instead of one.

Upvotes: 2

Sophie Alpert
Sophie Alpert

Reputation: 143134

[NSDecimalNumber numberWithDouble:myDouble]

Upvotes: 3

Chuck
Chuck

Reputation: 237040

NSNumber, the superclass of NSDecimalNumber, has a +numberWithDouble: method. That's what you want.

Upvotes: 14

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