Limiting decimal points to what is needed [duplicate]

Question

Possible Duplicate:
Rounding numbers in Objective-C
objective -C : how to truncate extra zero in float?
Correcting floating point numbers

In Objective C, I have a double which receives the answer to a calculation as shown:

double answer = a / b;

The double variable can sometimes be a whole integer but can also be a fraction e.g.

NSLog(@"%f", answer)

This can return 2.000000 or 5.142394 or 2.142000.

I was wondering if there was a way to edit the decimal places so that the trailing 0's are not visible for example:

2.000000 would be 2
5.142394 would be 5.142394
2.142000 would be 2.142

How can this be done?

Answer 1

If you'd like to hard-code the number of decimal places you're after, this would give you two decimal places:

NSLog(@"%.2f", answer);

Read more about format specifiers here:

http://www.cplusplus.com/reference/clibrary/cstdio/printf/

Alternatively, if you'd like to change the number of decimal places on-the-fly, consider using the NSNumberFormatter class:

int maxDigitsAfterDecimal = 3; // here's where you set the dp

NSNumberFormatter * nf = [[NSNumberFormatter alloc] init];
[nf setMaximumFractionDigits:maxDigitsAfterDecimal];

NSString * trimmed = [nf stringFromNumber:[NSNumber numberWithDouble:3.14159]];
NSLog(@"%@", trimmed); // in this case, 3.142

[nf release];