Question

If I use the following code:

- (NSString*)formatToCurrency:(float)inFloat {
  NSNumberFormatter *currencyFormatter = [[[NSNumberFormatter alloc] init] autorelease];
  [currencyFormatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
  [currencyFormatter setNumberStyle:NSNumberFormatterCurrencyStyle];
  [currencyFormatter setMaximumFractionDigits:2];
  [currencyFormatter setLocale:[NSLocale currentLocale]];

  NSNumber *x = [NSNumber numberWithFloat:inFloat];
  return [NSString stringWithFormat:@"  %@", [currencyFormatter stringFromNumber:x]];
}

then pass in 203500 when calling the code, I receive the output: $203,500.02.

I’d love to hear some thoughts on what is happening.

Thanks,

Matt

EDIT: XCode was reporting 203500 when I viewed it with the debugger, but when I converted the float to an NSString, it would also show 203500.018. Meaning the problem was in the float and not in the NSNumberFormatter.

Answer 1

You are creating the NSNumber with a float. Floats always can have a rounding error

What Every Computer Scientist Should Know About Floating-Point Arithmetic

You should familiarize yourself with NSDecimals and NSDecimalNumbers

Cocoa is my GF: Don’t be lazy with NSDecimalNumber (like me)