On Aug 23, 2010, at 1:35 AM, Adriano Brandão wrote:
> Thanks man, I tested here and it's working now.
>
> But, just for curiosity, if I was using only c++ wouldn't I be able to do
> that?
Using the C and C++ standard libraries only, you can't do that with the
provided formatters.
With the c-style "fF" conversions, the precision format specifies the number of
digits after the decimal point. There may be trailing zeros.
With the c-style "gG" conversion, the precision format specifies the maximum
number of significant digits to display, which is the total of the number of
digits before and after the decimal point. Trailing zeros after the decimal
point are stripped, and possibly the decimal point if there are only zeros
following.
This is equivalent for the iostream library where you set the precision using
the stream manipulator: setprecision().
In other words, there is no format specifier, which uses n digits after the
decimal point, and also strips the trailing zeros and possibly the decimal
point. Although the "gG" conversion strips trailing zeros after the decimal
point, it does not work for your problem, since it specifies the "maximum"
number of significant digits - you can't use it to specify n digits after the
decimal point.
>
>
> On 22/08/2010, at 19:04, Greg Parker wrote:
>
>> On Aug 21, 2010, at 9:59 AM, Adriano Brandão wrote:
>>> I'm having some troubles in formatting float numbers. If I wish to display
>>> 25.342 using only 2 decimal places I could use %.2f and it would do the
>>> job. But if the number to be formatted is flat (like 25.000) I get 25.00 as
>>> a result.
>>> After a little bit of research I found out that I could use # as a flag
>>> (%.#2f). But, even in this case, I get 25. (with the dot). So, what's the
>>> right way for displaying only 25 (mantaining the 2 decimal places for
>>> numbers that use them)?
>>
>> You can't get that result directly from printf(3), but you can do it with
>> NSNumberFormatter:
>>
>> {
>> NSNumberFormatter *fmt = [[NSNumberFormatter alloc] init];
>> [fmt setFormat:@"0.##"];
>> NSLog(@"%@", [fmt stringFromNumber:[NSNumber numberWithFloat:25.342]]);
>> NSLog(@"%@", [fmt stringFromNumber:[NSNumber numberWithFloat:25.3]]);
>> NSLog(@"%@", [fmt stringFromNumber:[NSNumber numberWithFloat:25.0]]);
>> }
>>
>> 2010-08-22 15:04:10.614 a.out[6954:903] 25.34
>> 2010-08-22 15:04:10.616 a.out[6954:903] 25.3
>> 2010-08-22 15:04:10.617 a.out[6954:903] 25
>>
>>
>> --
>> Greg Parker gpar...@apple.com Runtime Wrangler
>>
>>
>
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