A decidely non-challenging task to highlight a potential difference between programming languages.

Using a straightforward longhand loop as in the JavaScript and Phix examples below, show the locations of elements which are identical to the immediately preceding element in {1,2,2,3,4,4,5}. The (non-blank) results may be 2,5 for zero-based or 3,6 if one-based. 

The purpose is to determine whether variable declaration (in block scope) resets the contents on every iteration.

There is no particular judgement of right or wrong here, just a plain-speaking statement of subtle differences.

Should your first attempt bomb with "unassigned variable" exceptions, feel free to code it as (say)

 // int prev // crashes with unassigned variable
    int prev = -1 // predictably no output

If your programming language does not support block scope (eg assembly) it should be omitted from this task.

 
// Variable declaration reset. Nigel Galloway: June 21st 2022
let s=[1;2;2;3;4;4;5]
// First let me write this in real F#, which rather avoids the whole issue
printfn "Real F#"
s|>List.pairwise|>List.iteri(fun i (n,g)->if n=g then printfn "%d" (i+1))
// Now let me take the opportunity to write some awful F# by translating the C++
printfn "C++ like awful F#"
let mutable previousValue = -1
for i in 0..s.Length-1 do
  let currentValue=s.[i]
  if previousValue = currentValue then printfn "%d" i
  previousValue <- currentValue
 