Swift学习笔记(三)控制流
发布时间:2020-12-14 01:54:16 所属栏目:百科 来源:网络整理
导读:1.for-in 循环语句 for index in 1 ... 5 { println( "(index) times 5 is (index * 5)" )} 2.如果你不需要序列中的每一个值,你可以使用下划线来代替 let base = 3 let power = 10 var answer = 1 for _ in 1. ..power { answer *= base } 3.使用for-in去
1.for-in 循环语句 for index in 1...5 {
println("(index) times 5 is (index * 5)")
}
2.如果你不需要序列中的每一个值,你可以使用下划线来代替 let base = 3
let power = 10
var answer = 1
for _ in 1...power {
answer *= base
}
3.使用for-in去迭代遍历数组 let names = ["Anna","Alex","Brian","Jack"]
for name in names {
// println("Hello,(name)!")
}
4.for-in去迭代遍历字典 let numberOfLegs = ["spider": 8,"ant": 6,"cat": 4]
for (animalName,legCount) in numberOfLegs {
// println("(animalName)s have (legCount) legs")
}
5.for循环 (不能使用let,因为index自增) for var index = 0; index < 3; ++index {
println("index is (index)")
}
6.If语句 var temperatureInFahrenheit = 30
if temperatureInFahrenheit <= 32 {
println("It's very cold. Consider wearing a scarf.")
}
7.Switch let someCharacter: Character = "e"
switch someCharacter {
case "a","e","i","o","u":
println("(someCharacter) is a vowel")
case "b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","w","x","y","z":
println("(someCharacter) is a consonant")
default:
println("(someCharacter) is not a vowel or a consonant")
}
8.switch元组 let somePoint = (1, 1)
switch somePoint {
case (0, 0):
println("(0,0) is at the origin")
case (_, 0):
println("((somePoint.0),0) is on the x-axis")
case (0,_):
println("(0,(somePoint.1)) is on the y-axis")
case (-2...2, -2...2):
println("((somePoint.0),(somePoint.1)) is inside the box")
default:
println("((somePoint.0),(somePoint.1)) is outside of the box")
}
9.switch的case中可以使用where let yetAnotherPoint = (1,-1)
switch yetAnotherPoint {
case let (x,y) where x == y:
println("((x),(y)) is on the line x == y")
case let (x,y) where x == -y:
println("((x),(y)) is on the line x == -y")
case let (x,y):
println("((x),(y)) is just some arbitrary point")
}
// prints "(1,-1) is on the line x == -y"
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