Round doubles in Objective-C

Question

I have double number in a format like 34.123456789. How can I change it to 34.123?

I just want 3 digits after the decimal point.

Answer 1

You can print it to 3 decimal places with [NSString stringWithFormat:@"%.3f",d].

You can approximately round it with round(d*1000)/1000, but of course this isn't guaranteed to be exact since 1000 isn't a power of 2.