How do I round a NSNumber to zero decimal spaces

Question

How do I round an NSNumber to zero decimal spaces, in the following line it seems to keep the decimal spaces:

NSNumber holidayNightCount = [NSNumber numberWithDouble:sHolidayDuration.value];

duplicate http://stackoverflow.com/questions/576110/nstimeinterval-to-readable-nsnumber — AndersK, Aug 02 '10 at 13:22

score 14 · Answer 1 · edited Mar 25 '16 at 16:47

14

Typically casting to int truncates. For example, 3.4 becomes 3 (as is desired), but 3.9 becomes 3 also. If this happens, add 0.5 before casting

int myInt = (int)(sHolidayDuration.value + 0.5);

edited Mar 25 '16 at 16:47

Scott Marchant

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answered Aug 02 '10 at 13:38

Paul E.

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That is such a witty way of getting around the round up. I had never thought of doing it that way cause of built in rounding tools in ios. I like this answer a lot way to be thinking. – Rob Jul 02 '12 at 14:07
This wouldn't really work with negative numbers though – oztune Sep 21 '16 at 21:42
For negative numbers try this `int myInt = (int)(sHolidayDuration.value > 0 ? sHolidayDuration.value + 0.5 : sHolidayDuration.value - 0.5);` – mogelbuster Apr 29 '18 at 01:15

score 12 · Answer 2 · answered Sep 13 '11 at 14:37

12

Here's a bit of a long winded approach

float test = 1.9;
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setRoundingMode:NSNumberFormatterRoundHalfUp];
[formatter setMaximumFractionDigits:0];
NSLog(@"%@",[formatter  stringFromNumber:[NSNumber numberWithFloat:test]]);
[formatter release];

answered Sep 13 '11 at 14:37

pir800

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This is more what I was looking for. In my case I wanted a decimal place or two, and in that respect this method is more powerful. – csga5000 Nov 08 '15 at 02:06

score 3 · Accepted Answer · answered Aug 02 '10 at 13:28

3

If you only need an integer why not just use an int

int holidayNightCount = (int)sHolidayDuration.value;

By definition an int has no decimal places

If you need to use NSNumber, you could just cast the Double to Int and then use the int to create your NSNumber.

int myInt = (int)sHolidayDuration.value;
NSNumber holidayNightCount = [NSNumber numberWithInt:myInt];

answered Aug 02 '10 at 13:28

esde84

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floor is more likely the desired behavior – Joshua Weinberg Aug 02 '10 at 18:49
@JoshuaWeinberg Technically this should truncate, which is the same as floor. – csga5000 Nov 08 '15 at 02:07
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Floor and truncation are different for negatives. – Joshua Weinberg Nov 12 '15 at 21:03

score 1 · Answer 4 · answered Jul 19 '13 at 20:13

1

you can also do the following: int roundedRating = (int)round(rating.floatValue);

answered Jul 19 '13 at 20:13

kevinl

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score 0 · Answer 5 · answered Aug 28 '14 at 12:05

Floor the number using the old C function floor() and then you can create an NSInteger which is more appropriate, see: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/floor.3.html ....

NSInteger holidayNightCount = [NSNumber numberWithInteger:floor(sHolidayDuration.value)].integerValue;

Further information on the topic here: http://eureka.ykyuen.info/2010/07/19/objective-c-rounding-float-numbers/

Or you could use NSDecimalNumber features for rounding numbers.

How do I round a NSNumber to zero decimal spaces

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