Swift 2

var str = "Hello, playground"
let str1 = "swift"
let str2 = "1 + 2 = \(1+2)"

var str3 = "Hello"
str3 = str3 + "Swift"
str3.append("!")

let intVal = 123
let strFromInt = String(intVal)

let intStr = "1234"
let intValFromSrt = Int(intStr)

let num = Int("123a")

 

 

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let srt = "Hello Swift"

str.characters.count

str.startIndex
str.endIndex

let index3 = str.index(str.startIndex, offsetBy: 3)
let index7 = str.index(str.endIndex, offsetBy: -4)

let subStr = str[index3...index7]

 

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