How do I change the values of an array using a for-in loop inside a function or a nested function?

Question

Running through the swift 2.0 documentation and Im trying to practice some stuff I learned in c++. One of which is the ability to modify array elements inside of my element which I am having trouble doing in swift.

 var scoreOfStudents = [86, 93, 68, 78, 66, 87, 80]

 func returnScoresWithCurve (inout scoresOfClass : [Int]) -> [Int] {
      for var score in scoresOfClass {
          if score < 80 {
              score += 5
          }
      }
      return scoresOfClass
 }

Don't know what my error is because in the for-in loop, the scores less than 80 are being added but aren't being modified in the array I passed. Also would like to know how I can do this same thing using a nested function and not for-in loops.

Answer 1

I believe that using a for-in loop like this, your score variable is value copy of the array element, as opposed to a reference variable to the actual index of your array. I would iterate through the indices and modify scoresOfClass[index].

This should do what you're looking to do.

var scoreOfStudents = [86, 93, 68, 78, 66, 87, 80]

func returnScoresWithCurve(inout scoresOfClass: [Int]) -> [Int] {
    for index in scoresOfClass.indices {
        if scoresOfClass[index] < 80 {
            scoresOfClass[index] += 5
        }
    }
    return scoresOfClass
}

Also, why are you you using inout scoresOfClass when you're returning?