var iX = 9
var iY= 8
iX = iY//iX is 8

let (iX, iY = (8, 7)
// iX is 8, iY is 7

var iA = 1
var iB = 2
if iA = iB {
//编译出错
}

var strFirst = "tst "
var strSecond = "xx"
var strRes = strFirst + strSecond
println("\(strRes)")// tst xx


var chFirst : Character = "A"
var chSecond : Character = "i"// Character类型的也用 “”双引号
var strRes  = chFirst + chSecond

println("\(strRes)")

for index in 3...5 {
    println("\(index) time  is \(index * 5)")
}

3 time is 15
4 time is 20
5 time is 25