苹果Swift语言中文教程（三） 字符串和字符

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let wiseWords = ""Imagination is more important than knowledge" - Einstein"
// "Imagination is more important than knowledge" - Einstein
let dollarSign = "x24" // $, Unicode scalar U+0024
let blackHeart = "u2665" // ♥, Unicode scalar U+2665
let sparklingHeart = "U0001F496" // , Unicode scalar U+1F496

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var emptyString = "" // empty string literal
var anotherEmptyString = String() // initializer syntax
// these two strings are both empty, and are equivalent to each other

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if emptyString.isEmpty {
println("Nothing to see here")
}
// prints "Nothing to see here"

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var variableString = "Horse"
variableString += " and carriage"
// variableString is now "Horse and carriage"
let constantString = "Highlander"
constantString += " and another Highlander"
// this reports a compile-time error - a constant string cannot be modified

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for character in "Dog!" {
println(character)
}
// D
// o
// g
// !
//

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let yenSign: Character = "￥"

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let unusualMenagerie = "Koala , Snail , Penguin , Dromedary "
println("unusualMenagerie has (countElements(unusualMenagerie)) characters")
// prints "unusualMenagerie has 40 characters"

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let string1 = "hello"
let string2 = " there"
let character1: Character = "!"
let character2: Character = "?"
let stringPlusCharacter = string1 + character1 // equals "hello!"
let stringPlusString = string1 + string2 // equals "hello there"
let characterPlusString = character1 + string1 // equals "!hello"
let characterPlusCharacter = character1 + character2 // equals "!?"

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var instruction = "look over"
instruction += string2
// instruction now equals "look over there"
var welcome = "good morning"
welcome += character1
// welcome now equals "good morning!"

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let multiplier = 3
let message = "(multiplier) times 2.5 is (Double(multiplier) * 2.5)"
// message is "3 times 2.5 is 7.5"

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let quotation = "We're a lot alike, you and I."
let sameQuotation = "We're a lot alike, you and I."
if quotation == sameQuotation {
println("These two strings are considered equal")
}
// prints "These two strings are considered equal"
//输出”These two strings are considered equal”

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let romeoAndJuliet = [
"Act 1 Scene 1: Verona, A public place",
"Act 1 Scene 2: Capulet's mansion",
"Act 1 Scene 3: A room in Capulet's mansion",
"Act 1 Scene 4: A street outside Capulet's mansion",
"Act 1 Scene 5: The Great Hall in Capulet's mansion",
"Act 2 Scene 1: Outside Capulet's mansion",
"Act 2 Scene 2: Capulet's orchard",
"Act 2 Scene 3: Outside Friar Lawrence's cell",
"Act 2 Scene 4: A street in Verona",
"Act 2 Scene 5: Capulet's mansion",
"Act 2 Scene 6: Friar Lawrence's cell"
]

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var act1SceneCount = 0
for scene in romeoAndJuliet {
if scene.hasPrefix("Act 1 ") {
++act1SceneCount
}
}
println("There are (act1SceneCount) scenes in Act 1")
//输出”There are 5 scenes in Act 1”

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var mansionCount = 0
var cellCount = 0
for scene in romeoAndJuliet {
if scene.hasSuffix("Capulet's mansion") {
++mansionCount
} else if scene.hasSuffix("Friar Lawrence's cell") {
++cellCount
}
}
println("(mansionCount) mansion scenes; (cellCount) cell scenes")
// 输出 "6 mansion scenes; 2 cell scenes”

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let normal = "Could you help me, please?"
let shouty = normal.uppercaseString
// shouty is equal to "COULD YOU HELP ME, PLEASE?"
let whispered = normal.lowercaseString
// whispered is equal to "could you help me, please?"

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for codeUnit in dogString.utf8 {
print("(codeUnit) ")
}
print("n")
// 68 111 103 33 240 159 144 182

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for codeUnit in dogString.utf16 {
print("(codeUnit) ")
}
print("n")
// 68 111 103 33 55357 56374

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for scalar in dogString.unicodeScalars {
print("(scalar.value) ")
}
print("n")
// 68 111 103 33 128054