Chapter 22, Silver Challenge

Swift Programming (3rd Edition) 22. Protocol Extensions
1 
extension Collection where Element: Numeric  {
  var sum: Self.Element {
    var result: Self.Element = 0
    for num in self {
      result += num
    }
    return result
  }
}

[1, 2, 3].sum // 6
[2.5, 2.5].sum // 5
2

@mgmzlm: you might also use the reduce( ) function to (ha ha) reduce the number of lines of code in your extension.

let sum = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].reduce(0, { $0 + $1 })
print(“sum = (sum)”)

1 Like
3

Got it, thanks!

extension Sequence where Element: Numeric {
  var sum: Self.Element { reduce(0) { $0 + $1 } }
}