string - 在 Swift 中计算不同的字符

Question

我是 swift 的新手，我正在尝试 count string 中的不同 characters 但我的代码返回了整个值字符串

例如:

var string aString = "aabb"
aString.characters.count()             //returns 5

counter = 0
let a = "a"

for a in aString.characters {
  counter++
}                                      //equally returns 5

有人可以解释为什么会发生这种情况以及我如何计算不同的字符吗？

Answer 1

看起来您对真正需要的东西有些困惑。

我尝试回答 5 种最可能的解释。

var word = "aabb"

let numberOfChars = word.characters.count // 4
let numberOfDistinctChars = Set(word.characters).count // 2
let occurrenciesOfA = word.characters.filter { $0 == "A" }.count // 0
let occurrenciesOfa = word.characters.filter { $0 == "a" }.count // 2
let occurrenciesOfACaseInsensitive = word.characters.filter { $0 == "A" || $0 == "a" }.count // 2

print(occurrenciesOfA)
print(occurrenciesOfa)
print(occurrenciesOfACaseInsensitive)