Swift (i)

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  //Output functionprintln"Hello World")/Let define constant var define variable         LetLogincount= 5        varCurrentlogincount= 0//Logincount = 10//Burst red//Currentlogincount =println ((Logincount, Currentlogincount))//Remove parenthesis Error        //define multiple constants or variables in the same row         LetA= 1B= 2C= 3        varX= 4Y= 5Z= 6        varStr1= "STR1", str2= "STR2", STR3= "STR3"        //Type callout        //declares a variable of type String named Namestring        varNamestring:StringNamestring= "Cacaca"println ((namestring))//Let Count:int//for Xcode 6.3 and above//Count =//println ((count))        //variables, names of constants         LetWang= "high-rich handsome"        var??= "?"        //variables or constants cannot start with a number, but numbers can be placed in the middle or at the end         LetA2b2= 123;        println ((??)) println (Wang)//Output constants and variables        //Use the string difference to add the current variable name as a placeholder to the string, and then add parentheses and backslashes to transfer the output.         varJuicename= "Apple Juice"println ((juicename)) println (("I love \" (juicename)))varIosdevice= "IPhone6"println"I want to \ (Iosdevice) ぁゅゐ??")//Notes        //single-line comment        / * Multiline Comment * /        / * This is the beginning of the first multiline comment/* This is the beginning of the second multiline comment * /This is the end of the second multi-line comment, which is the end of the first multiline comment*/        //You must add a semicolon behind the statement        You need to add a semicolon when you need to add multiple independent statements in a row        var??= "Rubbit"; println (??) Letadb= Ten; println ((ADB));///8-bit signed integer type the minimum maximum value that can be represented         LetMinInt8=Int8.min         LetMaxInt8=Int8.Maxprintln ((MinInt8, maxInt8))///8-bit unsigned integer type can represent the maximum minimum value         LetMinUint8=UInt8.min         LetMaxUint8=UInt8.Maxprintln ((MinUint8, maxUint8))//16-bit signed integer type can represent the maximum minimum value         LetMinInt16=Int16.min         LetMaxInt16=Int16.Maxprintln ((minInt16, maxInt16))///16-bit unsigned integer type can represent the maximum minimum value         LetMinUint16=UInt16.min         LetMaxUint16=UInt16.Maxprintln ((minUint16, maxUint16))//32-bit signed integer type can represent the maximum minimum value         LetMinInt32=Int32.min         LetMaxInt32=Int32.Maxprintln ((MinInt32, MaxInt32))///32-bit unsigned integer type can represent the maximum minimum value         LetMinUint32=UInt32.min         LetMaxUint32=UInt32.Maxprintln ((MinUint32, MaxUint32))//64-bit signed integer type can represent the maximum minimum value         LetMinInt64=Int64.min         LetMaxInt64=Int64.Maxprintln ((MinInt64, MaxInt64))///64-bit unsigned integer type can represent the maximum minimum value         LetMinUint64=UInt64.min         LetMaxUint64=UInt64.Maxprintln ((MinUint64, MaxUint64))//Float accurate to 5 digits after decimal point        varπ:floatπ= 3.1415926println ((π))//double accurate to 14 digits after decimal point        varPi1:D oubleπ1 = 3.1415926535897932384println (π1))//Type safety        varStr= "IPhone"        //The system will automatically infer that STR is a String type        //Type safety, the top system is inferred as a String, the bottom of the assignment of other types, the compiler will directly error.         //str = 10;//compiler will burst red hint str is a String type,        varValue= Ten        //The system is automatically inferred as Int//value = "AGLKHELKHG" At the time of assignment the system will first type inference, the system is inferred to be an Int type, the bottom of the assignment is a String, the compiler will directly error, the hint type mismatch.          LetPdsu= 5 + 1.442        //The system will automatically infer the Double type        //numeric type conversions         LetValue1:uint16= 3200         LetValue2:uint8= 7        ///Two different numeric types cannot be added directly because the type does not match//Let Value3 = value1 + value2        //You need to convert a numeric type to the same type for other operations         LetValue3=Value1+UInt16 (value2) println ((VALUE3))varOne=  - //Type inferred to be of type Int        varBoth= 3.13  //Type inference to Double type        varThree=Double (one)+println ((three))//Type aliases        //Give a more meaningful name to the existing typeTypealias Audiosample=Int LetMaxValue=Audiosample.Maxprintln (MaxValue)//bool type, type will trigger type inference, inferred as bool type         LetAreyouok= true         LetAreyoulikeshit= false        ifAreyouok {println ((Areyouok))}if !Areyoulikeshit {println ((areyoulikeshit))}//Tuple         LetHttp404error=(404,"Not Found!")access to//meta-group data         Let(Messagecode, message)=Http404error println ("This is status code \ (Messagecode)") println ("This is status message \ (message)")//access by subscriptprintln"This is status code \ (http404error.0)") println ("This is status message \ (Http404error.1)")//If you only need a subset of the value of the tuple, you can break down the part you want to use _ Mark         Let(Justneedstatuscode, _)=Http404error println ("This is status code \ (Justneedstatuscode)") Let(_, Justneedstatusmessage)=Http404error println ("This is status message \ (justneedstatusmessage)")//You can name a single element when you define a tuple         LetHttp200status=(StatusCode: $, Message:"OK") println ("This is status code \ (Http200status.statuscode)") println ("This is status message \ (http200status.message)")//Optional type         LetPossablenumber= "123"         LetConvernumber=Possablenumber.ToInt ()//CONVERNUMEBR is inferred as "Int?" Or a Optional Int .        if  LetNumber=Possablenumber.ToInt () {println ("\ (possablenumber) has an integer value of \ (number)")        }Else{println ("\ (Possablenumber) could not convered integer")        }//Assertion         LetAge= -3ASSERT (age>= 0,"A person's age cound not being less than zero")

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Swift (i)