[swift-users] arc4random_uniform on Linux is missing from Foundation??

[Philippe Hausler]

arc4random_uniform is from Darwin not Foundation - it just happens to be in a header we import when you import Foundation.

> On May 22, 2017, at 8:44 AM, Edward Connell via swift-users <swift-users at swift.org> wrote:
> 
> Any ideas when Foundation on Linux will support arc4random_uniform? This is kind of an important function.
> There doesn't seem to be any decent substitute without requiring the installation of libbsd-dev, which turns out to be messy. Currently I am doing this, but glibc random with mod does not produce good quality numbers, due to modulo bias.
> 
> Has anyone come up with a better solution to get a true uniform distribution that isn't super messy?
>  
> import Foundation
> 
> #if os(Linux)
> 	import Glibc
> #endif
> 
> 
> public func random_uniform(range: Int) -> Int {
> 	guard range > 0 else { return 0 }
> 	#if os(Linux)
> 	  return Int(random()) % range
> 	#else
> 	  return Int(arc4random_uniform(UInt32(range)))
> 	#endif
> }
> 
> 
> Thanks, Ed
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