cocoa - converting a double to string

Question

I have a double number and I would like to convert it to string.

The number is, for example, something like

24.043333332154465777...

but if I convert it to string using something like

NSString *myString = [NSString stringWithFormat:@"%f", myDouble];

The string is just

24.043333

how do I get a full string the corresponds to the whole double number? What other methods do I have to convert this?

score 41 · Accepted Answer · answered Mar 18 '10 at 16:19

41

Another option, since you asked for other ways in your comment to mipadi's answer:

Create an NSNumber using NSNumber *myDoubleNumber = [NSNumber numberWithDouble:myDouble];

Then call [myDoubleNumber stringValue];

From the docs:

Returns the receiver’s value as a human-readable string, created by invoking descriptionWithLocale: where locale is nil.

answered Mar 18 '10 at 16:19

Jasarien

both methods - yours and mipadi's - are perfect for the conversion, but for some reason, mipadi's gave me a string that was slightly different of the original number. Your's give me the same number... thanks. – Duck Mar 18 '10 at 16:27

Hafthor · Answer 2 · 2014-02-21T19:41:09.447

23

[NSString stringWithFormat:@"%.20f", myDouble];

or

@(myDouble).stringValue;

edited Feb 21 '14 at 19:41

answered Dec 13 '12 at 05:00

Hafthor

score 13 · Answer 3 · answered Mar 18 '10 at 15:48

13

You can pass a width format specifier to stringWithFormat.

NSString *myString = [NSString stringWithFormat:@"%.20f", myDouble];

will format myDouble with 20 decimal places.

answered Mar 18 '10 at 15:48

mipadi

thanks!!! Just a final question. Is this the only way to convert a double to string? I mean, using stringWithFormat? – Duck Mar 18 '10 at 16:04
1

@Hafthor: No need for `lf`. `f` is the format specifier for a double, as noted in the Cocoa string documentation (https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265) and this question (http://stackoverflow.com/a/4264154/28804). – mipadi Jan 27 '14 at 18:10

score 2 · Answer 4 · answered Feb 21 '14 at 17:00

2

[NSString stringWithFormat:@"%.0f", myDouble];

Use this for no decimal value

answered Feb 21 '14 at 17:00

Anand Mishra

score 2 · Answer 5 · answered Mar 18 '10 at 17:19

2

answered Mar 18 '10 at 17:19

Peter Hosey

5 Answers5