Question

I want to find maximum, minimum and average in an array without .NET in F#.
I used this code but it is not working:

let mutable max = 0
let arrX = [|9; 11; 3; 4; 5; 6; 7; 8|]

for i in 0 .. arrX.Length - 2 do
  if (arrX.[i]) < (arrX.[i+1]) then 
       max <- arrX.[i]
       printfn "%i" max

Answer 1

I fixed your code for max

let mutable max = 0
let arrX= [|9; 11; 3; 4; 5; 6; 7; 8|]

for i in 0 .. arrX.Length - 1 do
  if max < (arrX.[i]) then 
       max <- arrX.[i]
       printfn "%i" max

To find max, min and avg, using your approach:

let mutable max = System.Int32.MinValue
let mutable min = System.Int32.MaxValue
let mutable sum = 0
let arrX= [|9; 11; 3; 4; 5; 6; 7; 8|]

for i in 0 .. arrX.Length - 1 do
  if max < (arrX.[i]) then 
       max <- arrX.[i]
       printfn "max %i" max
  if min > (arrX.[i]) then 
       min <- arrX.[i]
       printfn "min %i" min
  sum <- sum + arrX.[i]
printfn "-> max is %i" max
printfn "-> min is %i" min
printfn "-> avg is %f" (float sum / float arrX.Length)

But note you can do just:

let max = Seq.max arrX
let min = Seq.min arrX
let avg = Seq.averageBy float arrX