[Swift 官方教程]03 字符串和字符

let s = "hello"

let s = """
hear me now and bear witness to my vow
night gathers and now my watch begins
"""

let s = """
hear me now and bear witness\
to my vow
night gathers and now my watch begins
"""

let a = "\u{24}"        // $,  Unicode scalar U+0024
let b = "\u{2665}"      // ♥,  Unicode scalar U+2665
let c = "\u{1F496}" // 💖, Unicode scalar U+1F496

let s1 = #"Here are : \n"#
let s2 = ##"Here are : \n"##
let s3 = ###"Here are : \n"###

let s1 = #"Here are : \#n"#
let s2 = ##"Here are : \##n"##
let s3 = ###"Here are : \##n"###

var s1 = ""
var s2 = String() 

if s.isEmpty {
	...
}

for c in "Dog!🐶" {
    print(c)
}

let c: Character = "!"

let c: [Character] = ["C", "a", "t", "!", "🐱"]
let s = String(c)

let a = "hello"
let b = " world"
let s = a + b

var s = "hello"
s += " world"

var s = "hello"
s.append("!")

var a = "root"
let b = "hello \(a)"

print(#"6 times 7 is \#(6 * 7)."#)

let a: Character = "\u{E9}"
let b: Character = "\u{65}\u{301}" 
print(a == b) // true

let a: Character = "\u{D55C}" // 한 
let b: Character = "\u{1112}\u{1161}\u{11AB}" // ᄒ, ᅡ, ᆫ
print(a == b) // true

let a: Character = "\u{E9}\u{20DD}"

let a: Character = "\u{1F1FA}\u{1F1F8}"
print(a) // 🇺🇸

var s = "root"
print(s.count) // 4

let s = "abcdefg"

s[s.startIndex] // a

s[s.index(before: s.endIndex)] // g
s[s.index(after: s.startIndex)] // b

let index = s.index(s.startIndex, offsetBy: 3)
print(s[index]) // d

for i in s.indices {
    print(s[i])
}

var s = "abcdefg"

s.insert("h", at: s.endIndex)

s.remove(at: s.index(before: s.endIndex))

let range = s.index(s.endIndex, offsetBy: -2) ..< s.endIndex
s.removeSubrange(range)

var s = "abc,def,g"
let index = s.firstIndex(of: ",") ?? s.endIndex
let a = s[..<index]

let b = String(a)

let a = "I'm root"
let b = "I'm root"
if a == b {
    print("equal")
}

let a = "Voulez-vous un caf\u{E9}?"
let b = "Voulez-vous un caf\u{65}\u{301}?"
if a == b {
    print("equal")
}

let list = [
    "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"
]

for i in list {
    if i.hasPrefix("Act 1") { // 是否拥有前缀
        print("prefix")
    }
    
    if i.hasSuffix("cell") { // 是否拥有后缀
        print("suffix")
    }
}

let dogString = "Dog‼🐶"

for codeUnit in dogString.utf8 {
    print("\(codeUnit) ", terminator: "")
}
// 68 111 103 226 128 188 240 159 144 182

for codeUnit in dogString.utf16 {
    print("\(codeUnit) ", terminator: "")
}
// 68 111 103 8252 55357 56374 

for scalar in dogString.unicodeScalars {
    print("\(scalar.value) ", terminator: "")
}
// 68 111 103 8252 128054 

for scalar in dogString.unicodeScalars {
    print("\(scalar) ")
}
// D
// o
// g
// ‼
// 🐶