firstTwoChars = * and lastTwoChars = *

starId.swift

//  Created by Kenny Dubroff on 10/14/18.

var str = "p123869"

var chars = Array(str)
//first 2 characters are always 0 and 1
chars[0] = "*"
chars [1] = "*"

///endIndex is always one greater than the last index
let endIndex = chars.endIndex - 1
let nextToEndIndex = endIndex - 1

chars[endIndex] = "*"
chars[nextToEndIndex] = "*"

print(chars) //**238**