Got a question about my random function: why is it giving this error?
'4294967295' is not exactly representable as 'Float'; it becomes '4294967296'
-
my code is
func random() ->CGFloat {
return CGFloat(Float(arc4random()) / 0xFFFFFFFF)
}
func random(min: CGFloat, max: CGFloat) -> CGFloat {
return random() * (max - min) + min
}
it doesn't change the functionality of the application but it just appeared out of nowhere.
thanks in advance!
A IEEE 754 32-bit floating point number has 24 significant bits for the mantissa, that is not enough to store a 10-digit integer exactly:
print(0xFFFFFFFF) // 4294967295
print(Float(0xFFFFFFFF)) // 4.2949673e+09
print(Int(Float(0xFFFFFFFF))) // 4294967296
That won't affect your code because
Float(arc4random()) / Float(0xFFFFFFFF)
is still a floating point number between 0.0 and 1.0. Changing the calculation to
return CGFloat(arc4random()) / 0xFFFFFFFF
will fix the warning on 64-bit platforms: The integer constant is now converted to a (64-bit) Double.
But as of Swift 4.2 you can avoid the problem completely by using the new Random API:
func random(min: CGFloat, max: CGFloat) -> CGFloat {
return CGFloat.random(in: min...max)
}