questions3.md

Topics covered

• String manipulation (substrings)
• typealias protocol

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Question 1

• Given: Array of strings of various lengths
• Task: Return array of strings where the last 2 characters are uppercased

• Hint: Need at least 2 characters to perform this
• Hint: Write function to make this change to a single string
• Hint: String indexing requires .index, where you have to specify str.startIndex / .endIndex

• There is a variant of this function that takes an offset

Solution:

extension String {

  func length() -> Int {
    return self.characters.count
  }

  func wholeStr() -> String {
    let endStartIndex = index(endIndex, offsetBy: -2)
    let firstRange = startIndex..<endStartIndex
    let secondRange = endStartIndex..<endIndex

    return String(self[firstRange] + self[secondRange].uppercased())
  }
}

let strArr: [String?] = ["Do", "Connor", "Kyle", "A", "", nil]
print(strArr.flatMap { $0 }.filter { $0.length() >= 2 }.map { $0.wholeStr() })

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Question 2

Given a struct, typealias it to another name

Solution:

struct Connor {}

let a = Connor()
typealias Kyle = Connor

let b = Kyle()

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