控制流
順序結構
循環結構
選擇結構
/*for in 方法中存在忽略遍歷的 i的情況,只關注便利次數*/
var result = 1
var base = 2
var power = 10
for _ in 1 ... power{
resulet *= base
}
result 的值爲1024;
for in 的 第二種形式
for var i = -99 ; i<= 99 i ++{
i*i
}
//也可以寫成
var i = -99
for ; i<= 99 ;{
i*i
i++
}
還有比較符載的情況
var insex = -99
var step = 1
for ; index <= 99 ; index += setp{
index *index
setp *= 2
}
邏輯控制循環值while和repeat
while
while condition{
statements
increments
}
下面是一個正篩子的小遊戲
//: Playground - noun: a place where people can play
import UIKit
var aWin = 0
var bWin = 0
var count = 0
while (aWin < 3 && bWin < 3) {
count += 1
let a = arc4random_uniform(5)+1
let b = arc4random_uniform(5)+1
print("a is\(a),b is \(b).",terminator:"")
if a<b {
aWin = 0
bWin += 1
}else if a>b{
aWin += 1
bWin = 0
}else{
print("draw")
aWin = 0
bWin = 0
}
}
let winner = aWin == 3 ? "A" : "B"
print("after \(count) games ,\(winner) win!")
鄭骰子 比大小
//: Playground - noun: a place where people can play
import UIKit
while true {
let a = arc4random_uniform(5)+1
let b = arc4random_uniform(5)+1
if(a == b){
print("deaw")
continue
}
let winner = a > b ? "a" : "b"
print(winner)
break
}
SWITCH:
java中的基本數據類型也可以switch case語句來判斷哦,java在很多地方都與swift有相似之處,有java基礎的人來學swift應該會事半功倍
switch在判斷變量時候,必須要把所有數據窮舉了,否則就咬加上default
switch不緊可以判斷值,即還可判斷區間,還可以判斷元組,
fallthrough關鍵字,告訴case語句,在執行完後可以繼續執行下一個語句,