04--swift之流程控制

1.for
var a = [1,2,3]
for e in a{
print(e)
}
var dic = [1:"tom",2:"kite",3:"rose"]
for (key,value) in dic{
print("\(key):\(value)")
}
for e in 1..<10{
print(e)
}
2.while
var i = 1
var sum = 0
while i<=100{
sum += i
i++
}
print(sum)
//repeat while
var i = 1
var sum = 0
repeat{
sum += i
i++
}while i<=100
print(sum)
3.if else
var flag = true
if flag{
print("true")
}

var a = 1,b = 2
if a>b{
print(a)
}else{
print(b)
}
//if else if
var score = 90
if score>=90{
print("优")
}else if score<90&&score>=80{
print("良")

}else{
print("差")
}
4.switch
条件可以是整形之外的类型，如字符串
不用break，case后面可以有多个条件，必须有default，而且case，default后面必须有语句
var diction = "east"
switch diction{
case "east":
print("east")
case "west":
print("west")
case "south":
print("south")
case "north":
print("north")
default:
print("default")
}
//case后面有多个条件
var direction = "up"
switch direction{
case "up","top","上面":
print("up")
case "down","bottom":
print("down")
default:
print("default")
}
//范围匹配
var score = 90
switch score {
case 90...100:
print("very good")
case 80..<90:
print("good")
case 60..<80:
print("poor")
default:
print("default")
}
//switch值绑定
let point = (0,2)
switch point {
case (1,let y):
print("y=\(y)")
case (let x,2):
print("x=\(x)")
default:
print("default")
}
//case where
let point = (1,-1)
switch point {
case let (x,y) where x==y:
print("\(x),\(y) is x==y")
case let (x,y) where x == -y:
print("\(x),\(y) is x==-y")
default :
print("default")
}