检查字符是小写还是大写

Question

我正在尝试编写一个程序，将字符串存储在名为 input 的变量中。

使用这个 input 变量，然后我尝试将其转换为数组，然后使用 for 循环测试数组中的每个字符是否为小写。我怎样才能做到这一点？

这是我的进展：

var input = "The quick BroWn fOX jumpS Over tHe lazY DOg"

var inputArray = Array(input)

for character in inputArray {
    /*

    if character is lower case {

        make it uppercase

    } else {

        make it lowercase

    }

    */
}

Answer 1

您可以检查每个字符的ascii值，因为大写和小写是不同的值，因为大写是65-90，小写是97-122

Answer 2

您应该使用正则表达式：grep [A-Z] 与 grep [a-z]。

Answer 3

 var input = "The quick BroWn fOX jumpS Over tHe lazY DOg"

 var inputArray = Array(input)

 for character in inputArray {

 var strLower = "[a-z]";

 var strChar = NSString(format: "%c",character )
 let strTest = NSPredicate(format:"SELF MATCHES %@", strLower );
 if strTest .evaluateWithObject(strChar)
 {
   // lower character
 }
 else
 {
   // upper character
 }
}

Answer 4

Swift 3

static func isLowercase(string: String) -> Bool {
    let set = CharacterSet.lowercaseLetters

    if let scala = UnicodeScalar(string) {
      return set.contains(scala)
    } else {
      return false
    }
  }

Answer 5

Swift 4:

var input = "The quick BroWn fOX jumpS Over tHe lazY DOg"
let uppers = CharacterSet.uppercaseLetters
let lowers = CharacterSet.lowercaseLetters
input.unicodeScalars.forEach {
    if uppers.contains([=10=]) {
        print("upper: \([=10=])")
    } else if lowers.contains([=10=]) {
        print("lower: \([=10=])")
    }
}

Answer 6

这是写在 Swift 4 上的答案，无论输入字符串是单个字母还是多个字母，它都有效：

  extension String {
      static func isLowercase(string: String) -> Bool {
          let set = CharacterSet.lowercaseLetters
          for character in string {
              if let scala = UnicodeScalar(String(character)) {
                  if !set.contains(scala) {
                      return false
                  }
              }
          }
          return true
      }

      static func isUppercase(string: String) -> Bool {
          let set = CharacterSet.uppercaseLetters
          for character in string {
              if let scala = UnicodeScalar(String(character)) {
                  if !set.contains(scala) {
                      return false
                  }
              }
          }
          return true
      }
  }

Answer 7

如果必须的话，我可能会编写如下代码：

extension Character {
    func isMember(of set: CharacterSet) -> Bool {
        guard let scalar = UnicodeScalar(String(self)) else { return false }
        return set.contains(scalar)
    }
    var isUppercase: Bool {
        return isMember(of: .uppercaseLetters)
    }
    // var isLowercase, isWhitespace, etc.
}

let result = "The quick BroWn fOX jumpS Over tHe lazY DOg"
    .map { [=10=].isUppercase ? String([=10=]).lowercased() : String([=10=]).uppercased() }
    .joined()
print(result)

// "tHE QUICK bROwN Fox JUMPs oVER ThE LAZy doG"

Answer 8

基于字符比较的解决方案

let input = "The quick BroWn fOX jumpS Over tHe lazY DOg"

for char in input {
    if char >= "A" && char <= "Z" {
        print("upper: \(char)")
    } else if char >= "a" && char <= "z" {
        print("lower: \(char)")
    } else {
        print("something else: '\(char)'")
    }
}

检查字符是小写还是大写

Check if a character is lowerCase or upperCase

lowercase

swift