编辑代码

import Foundation


let names = ["Anna", "Alex", "Brian", "Jack"]
let count = names.count
for i in 0..<count {
//	print("第 \(i + 1) 个人叫 \(names[i])")
}
// 第 1 个人叫 Anna
// 第 2 个人叫 Alex
// 第 3 个人叫 Brian
// 第 4 个人叫 Jack
let range = ...2
//print(range)
for name in names[range] {
//    print(name)
}
print(range.contains(3))
var k=0
k+=1
struct Vector2D {
    var x = 0.0, y = 0.0
}

extension Vector2D {
    static func + (left: Vector2D, right: Vector2D) -> Vector2D {
        return Vector2D(x: left.x + right.x, y: left.y + right.y)
    }
}

let vector1 = Vector2D(x: 1.0, y: 2.0)
let vector2 = Vector2D(x: 3.0, y: 4.0)
let vectorSum = vector1 + vector2
print(vectorSum) // 输出结果为Vector2D(x: 4.0, y: 6.0)

postfix operator --
postfix func -- (num: inout Int) -> Int {
    num -= 1
    return num
}
var number = 5
print(number--) // 输出结果为4
let threeMoreDoubleQuotationMarks = """
Here are three more double quotes: 
"""
print(threeMoreDoubleQuotationMarks)

let greeting = "Guten Tag!"
print(greeting[greeting.startIndex])
// G
print(greeting[greeting.index(before: greeting.endIndex)])
// !
print(greeting[greeting.index(after: greeting.startIndex)])
// u
let index = greeting.index(greeting.startIndex, offsetBy: 7)
print(greeting[index])
// a
for greet in greeting {
    print(greet, terminator: "")
}
print("")
//Guten Tag!
var knames = ["ab","cd","ef","12","345","678"]
knames+=["1123","890"]
knames[2...6]=["a1123","a890"]
print("Count:\(knames.count)")
for (index,kname) in knames.enumerated() {
//    print("\(index + 1),\(kname)")
}
var letter = Set<Character>()
letter.insert("a")
letter.insert("b")
letter.insert("c")
//letter.append("b")
let lv=letter.sorted()
print(lv)
let da :[Int:String] = [1:"ab",2:"cd"]
print(da[2]!)

func funcName<T:BinaryFloatingPoint>(_ value: T) -> CGFloat {
  let num:CGFloat = CGFloat(value)
  return num
}

func funcName<T:BinaryInteger>(_ value: T) {
  let num:CGFloat = CGFloat(value)
}
let fa: CGFloat=funcName(10.2)
let ia: CGFloat=funcName(10)
print("\(ia),\(fa)")