/**

字符串的構造

*/

let str1 = "hello"

let str2 = "world"



// 拼接 沒有減號哦

let str3 = str1 + str2

print(str3)



let index = 9



let urlHead = "http://www.mobiletrain.org/"



let message = "\(urlHead)/pic/\(index).png"

print(message)