Absolute Value (abs) of NSDecimalNumber without loss of precision

Question

I need to get the absolute value of an NSDecimalNumber without loss of precision. I can\'t seem to find a way to do this without converting to decimal or float (with a loss

Answer 1

You can use the built-in functions of the NSDecimalNumber class to compare the number to zero, then multiply by -1 as appropriate. For example:

- (NSDecimalNumber *)abs:(NSDecimalNumber *)num {
    if ([num compare:[NSDecimalNumber zero]] == NSOrderedAscending) {
        // Number is negative. Multiply by -1
        NSDecimalNumber * negativeOne = [NSDecimalNumber decimalNumberWithMantissa:1
                                                                          exponent:0
                                                                        isNegative:YES];
        return [num decimalNumberByMultiplyingBy:negativeOne];
    } else {
        return num;
    }
}

Since this method works solely with NSDecimalNumbers, there's no loss of precision.