Day1 (Let and Var)/(String,int,float,double)/(Tuples,contains:array,dictionary)

Let secondsystem:Int = 0b10001

Let eightsystem:Int = 0o21

Let tensystem:Int =

Let sixthsystem:Int = 0x11

SUMMARY:1.U need insert a "Enter" behind equal symbol

Let num_a:Float = 1

Let num_b:Int = 1

Let A:Int = 3

Let B:Double = 0.1415926

Let pi:double = double(a) + b

summary:2.it need change-number ' s type in the same, in order to getting the result

Let bignum_a:Float = Ten/2.5

Let bignum_a2:Int = Ten/3

Let bignum_b:float = float(Int(1.2)) *10.1

Let bignum_c:int = int(3.99)

summary:3.it need change-number ' s type in the same, in order to getting the result

4.forcing number type need add type symbol in the front of number

Let jy = " Love Cooking "

Let address = ". Jianggan,hangzhou City,zhejiang Province,china "

JY + address

Let params = (isloginsuccess:true, Name:"Tommy", Age:)

Let (isloginsuccess,name,age) = params

Let islginsuccess = params. 0

Let whats = params. Name

Let whatsage = params. 2

Let (IsTrue,_,_) = params

If (isTrue)

{

Print("Login success!" )

}

Let Personarray = ("A","B","C","D")

Let Aperson = personarray. 0

Let Bperson = personarray. 1

Summary:5. Tuples

var value_a:Int

Value_a = 1

var imoptionalvariable:Int?

Summary:it ' s equal to nil when the optionalvariable is empty

Imoptionalvariable =

Let name = "Tommy"

var age = Int(name)

If age! = Nil

{

Print("It ' s not empty")

}

else {

Print("It ' s empty!" )

}

Let userage = " "

var currentage = Int(userage)

Let currentnewage = Int(userage)

Summary:string toint use Method:int (String)

If currentage! = nil

{

Print("Age: \(currentage)")

Print("He is" + String(currentage!))

}

If userage . IsEmpty

{

Print("Age: \(userage)")

}Else {

Print("Age:\(userage)")

}

Let Stringa:String? = "optional_string"

Let string2 = "_/stringa"

var stringb = Stringa! + string2

Stringa

Stringa!

Day1 (Let and Var)/(String,int,float,double)/(Tuples,contains:array,dictionary)