How to add commas to number every 3 digits in Objective C?

Question

If I have a number int aNum = 2000000 how do I format this so that I can display it as the NSString 2,000,000?

Answer 1

Use NSNumberFormatter.

Specifically:

NSNumberFormatter *formatter = [NSNumberFormatter new]; [formatter setNumberStyle:NSNumberFormatterDecimalStyle]; // this line is important!  NSString *formatted = [formatter stringFromNumber:[NSNumber numberWithInteger:2000000]];  [formatter release]; 

By default NSNumberFormatter uses the current locale so the grouping separators are set to their correct values by default. The key thing is to remember to set a number style.

Answer 2

Don't do your own number formatting. You will almost certainly not get all the edge cases right or correctly handle all possible locales. Use the NSNumberFormatter for formatting numeric data to a localized string representation.

You would use the NSNumberFormatter instance method -setGroupingSeparator: to set the grouping separator to @"," (or better yet [[NSLocale currentLocale] objectForKey:NSLocaleGroupingSeparator]; thanks @ntesler) and -setGroupingSize: to put a grouping separator every 3 digits.