"Swift-Summary" function

The use of Swift's functions has changed a lot in swift2.

/***param: personName 参数*returns: String为返回值*/func sayHello(personName: String) -> String {    return"Hello " + personName;}

/*swift2中函数的调用必须要使用标签或者别名，没有别名第一个标签不带*/func add(a: Int, b: Int) -> Int {    return a + b;}print(add(1b:2));

/*如果使用了别名，函数调用的时候必须使用别名*/func add(num1 a: Int, b: Int) -> Int {    return a + b;}print(add(num11b:2));

Return multiple values

/ * Returns multiple values, which is the return of a tuple * /varNums = [1,2,3,4,5]func Minmax (Array: [Int]), (Min:int, Max:int) {varMinnum =Array[0];varMaxnum =Array[0]; forNum inArray{ifNum < minnum {minnum = num}Else ifnum > Maxnum {maxnum = num}}return(Minnum, maxnum);}Print(Minmax (nums). Max);Print(Minmax (nums). min);

Returns an optional tuple

varNums = [1,2,3,4,5]func Minmax (Array: [Int]) (Min:int, max:int)? {if Array. isEmpty {returnNil }varMinnum =Array[0];varMaxnum =Array[0]; forNum inArray{ifNum < minnum {minnum = num}Else ifnum > Maxnum {maxnum = num}}return(Minnum, maxnum);}Print(Minmax (nums)!. MAX);Print(Minmax (nums)!. MIN);

Default parameters

numFun(num: Int = 22) {    print(num);}numFun();//输出22

Variable parameters

func numAdd(nums: Int...) {    varsum=0;    in nums {        sum+= num;    }    print(sum);}numAdd(123);

The case of calling functions without tags

func addNum(_ a:Int, _ b: Int) {   a + b;}addNum(a, b);

Variable parameters

function parameters are constants by default and cannot be changed inside the function values
To change the value of a parameter inside a function, use a variable as a parameter

func swapNum(varvar b: Int) {    var temp = a;    a = b;    b = temp;}

In-out parameters

The function defaults to using the copy transfer function
Using the In-out modifier parameter to indicate that the parameter is using a pointer transfer function

ab: Int) {    let temp = a;    a = b;    b = temp;}var1;var2b: &b);print("a is \(a), b is \(b)");

function type

func add(a: Int, b: Int) -> Int {    return a + b;}print1b:2));/*声明一个变量，后面是函数类型*/varaddNum(Int, Int) -> Int = add;print(addNum(23));

function type as parameter

func result(numFun: (Int, Int) -> Int, a: Int, b: Int) {    print(numFun(a, b));}result(addNum, a: 6, b: 7);

function type as return value

/*返回一个函数*/func chooseFunc() ->(Int) -> Int {}

Nested functions

func addNum(a: Int, b: Int) {    func printNum() {        print(22);    }    printNum();    print(a + b);}var a = 1;var b = 3;addNum(a, b:b);

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"Swift-Summary" function