17.闭区间和半开区间

for index in (1...5) {//闭区间
print("\(index) times 5 is \(index)")
}
//相当于定义一个变量i i>=1 && i <= 5.

var 群主名单 = ["群主1","群主2","群主3","群主4"]
var 群主数目 = 群主名单.count
for 排列顺序 in 0..<群主名单.count {
print("第\(排列顺序)个群主是\(群主名单[排列顺序])")
}