Console input giving spurious values

Question

After trying this simple console input with 5, the result is shown as 53

printfn "Enter no. of blocks: "
let nBlock = System.Console.Read()
printfn "entered value is %O" nBlock

Tried it on the interactive, still getting wrong results. Any solutions please?

Answer 1

You should try something like:

printfn "Enter no. of blocks: "
let nBlock = System.Console.ReadLine() |> System.Int32.Parse
printfn "entered value is %d" nBlock

Explanation:

you code only reads one character - as Lee mentioned with this you will read a line (ending after you press return) and parse that string into a int.

Remark: maybe you will want to check for a number, you can do this with TryParse:

printfn "Enter no. of blocks: "
let nBlock = 
   match System.Console.ReadLine() |> System.Int32.TryParse with
   | true, n -> n
   | false, _ -> -1
printfn "entered value is %d" nBlock

Of course you will have to check for the error case (-1) or change it into a option or something.

Answer 2

System.Console.Read() returns an int, therefore nBlock contains the int representation of the input character '5', which is 53. You can convert it back to a char using Convert.ToChar. Since each character is returned individually, you will need wrapping it into a loop to process the entire input, as described in this article.

A better approach is probably to use Console.ReadLine() to read then entire line and parse that to an int.