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iOS

Posted by Cody Adkins
Cody Adkins
7,260 Points

What is the difference between a Float and a Double?

Are they both used in the same way?

Kirill Babkin
Kirill Babkin
19,940 Points

hey float - "32 bit" is smaller than double.

double -"double precision 64-bit " it allows you to work with large numbers.

double can be twice smaller or twice large than float.

Cody Adkins
Cody Adkins
7,260 Points

Is there an advantage for using a float over a double if it is 32 bit? Or are you safe to always use a double?

2 Answers

Martin Wildfeuer
Martin Wildfeuer
Courses Plus Student 11,071 Points

Let me cite the Apple docs: Floating-Point Numbers here:

  • Double represents a 64-bit floating-point number, has a precision of at least 15 decimal digits
  • Float represents a 32-bit floating-point number, can have a precision as little as 6 decimal digits

In situations where either type would be appropriate, Double is preferred.

Swift also follows that convention by inferring floating point numbers as Double by default.

// pi is inferred to be of type Double
let pi = 3.14159

Hope that helps :)

Kirill Babkin
Kirill Babkin
19,940 Points
Kirill Babkin
Kirill Babkin
19,940 Points

i would think your are safe with any type you choose, floats should be sufficient in most cases. my professor told me to use doubles when dealing with an astronomically large numbers.