[swift-users] Looping through all values between UInt8.min and UInt8.max

[Milos Rankovic]

Hi Erica, 

Wouldn’t this work for @tuuranton’s purposes?


let allUInt8s = UInt8.min.stride(through: UInt8.max, by: 1)

allUInt8s.dynamicType // StrideThrough<UInt8>.Type

Array(allUInt8s).count // 256

for i in allUInt8s {
	i // 0...255
}

milos

> On 8 Apr 2016, at 13:48, tuuranton--- via swift-users <swift-users at swift.org <mailto:swift-users at swift.org>> wrote:
> 
> The problem with both solutions is that I lose the type information. Instead of i being UInt8 it is Int or UInt.
> 
> This is one solution I came up with:
> 
> extension UInt8 {
>     static var allValues: [UInt8] {
>         var v: [UInt8] = []
>         for i in 0..<UInt8.max {
>             v.append(i)
>         }
>         v.append(UInt8.max)
>         return v
>     }
> }
> 
> print(UInt8.allValues)
> 
> In other words, loop from 0 to 254 and then add 255 manually at the end.
> 
> Is there currently no simpler way to do this in Swift?
> 
> Idea for the Swift developers: Create a Bounded protocol that UInt8 (and the other integer types) conform to. Then add a "allValues" type method in that protocol. And also put .min and .max into that protocol. Currently it seems like .min and .max are not a part of any particular protocol.
> 
> 
> 8. Apr 2016 14:35 by swift-users at swift.org <mailto:swift-users at swift.org>:
> 
> You could cast the min and max values to an Int and iterate through the Int range:
> 
> let min = Int(UInt8.min)
> let max = Int(UInt8.max)
> 
> for i in min...max {
>     print(i)
> }
> 
> While this will work it seems like a hack to me and Milos’ solution is more elegant…
> 
> -Pete
> 
> 
> On Apr 8, 2016, at 5:50 AM, tuuranton--- via swift-users <swift-users at swift.org <mailto:swift-users at swift.org>> wrote:
> 
> I forgot to mention that I really would like to have i have type UInt8 within the loop. And since i is UInt8 it makes sense it should be able to take the values UInt8.min and UInt8.max (and all the values between).
> 
> 8. Apr 2016 11:48 by swift-users at swift.org <mailto:swift-users at swift.org>:
> 
> print(UInt8.min) //0
> 
> print(UInt8.max) //255
> 
> 
> 
> //Is there an easy way to loop between all values
> 
> //between (and including both) UInt8.min and UInt8.max?
> 
> 
> 
> //This doesn't work.
> 
> //Runtime crash because UInt8.max has no successor.
> 
> for i in UInt8.min...UInt8.max {
> 
>     print(i)
> 
> }
> 
> 
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org <mailto:swift-users at swift.org>
> https://lists.swift.org/mailman/listinfo/swift-users <https://lists.swift.org/mailman/listinfo/swift-users>
> 
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org <mailto:swift-users at swift.org>
> https://lists.swift.org/mailman/listinfo/swift-users

> On 8 Apr 2016, at 15:21, Erica Sadun via swift-users <swift-users at swift.org> wrote:
> 
>> 
>> On Apr 8, 2016, at 3:48 AM, tuuranton--- via swift-users <swift-users at swift.org <mailto:swift-users at swift.org>> wrote:
>> 
>> print(UInt8.min) //0
>> 
>> print(UInt8.max) //255
>> 
>> 
>> 
>> //Is there an easy way to loop between all values
>> 
>> //between (and including both) UInt8.min and UInt8.max?
>> 
>> 
>> 
>> //This doesn't work.
>> 
>> //Runtime crash because UInt8.max has no successor.
>> 
>> for i in UInt8.min...UInt8.max {
>> 
>>     print(i)
>> 
>> }
>> 
>> 
> 
> Easy? No. 
> 
> // Range Index has no valid successor
> for i in UInt8.min ... UInt8.max {
>     print(i)
> }
> 
> // '...' cannot be applied to two 'UInt8' operands
> for i in UInt8.min ... UInt8.max as ClosedInterval {
>     print(i)
> }
> 
> // Stops at 254
> for i in UInt8.min ..< UInt8.max {
>     print(i)
> }
> 
> 
> This works, but ugh:
> 
> for i : Int in numericCast(UInt8.min)...numericCast(UInt8.max) {
>     guard let j: UInt8 = UInt8(i) else { fatalError("Nope") }
>     print(j)
> }
> 
> cc'ing in a few people to the white courtesy range phone.
> 
> -- E
> 
> 
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org <mailto:swift-users at swift.org>
> https://lists.swift.org/mailman/listinfo/swift-users <https://lists.swift.org/mailman/listinfo/swift-users>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-users/attachments/20160408/6787a2b8/attachment.html>