Golang Basic--func function

Functional function

• The GO function does not support nesting, overloading, and default parameters

• The following features are supported:

  No need to declare prototypes, variable length length arguments, multiple return values, named return value parameters, anonymous functions, closures

• The

• Definition function uses the keyword func, and the left brace cannot be another line

    package Mainimport ("FMT") func main () {A, B: = 1, 2 D (A, B)//pass variable length variable, cannot modify slice index, cannot change slice value at all s1: = []int{1, 2, 3} D1 (S1)//pass slice as parameter, modify index value can achieve effect of modifying original slice x: =  1 D2 (&X)//Pass x memory address}//Parameter return value func a (a int, b string) int {return a}//multiple return values Func B () (A, B, c int) {//No parameters, A, b, C = 1, 2, 3//Because the return value already has a,b,c occupy the inner layer, so directly after the assignment return a, B, c//can omit a,b,c}//variable length arguments, that is, the int parameter can be multiple, passed in is a slice type func C (b String, a ... int) {FMT. Println (a)//output [1,2,3,4,5]}/variable-length parameter pass, passing in variables func D (s ... int) {FMT. Println (s) s[0] = 3 S[1] = 4 FMT. Println (s)}//passes slice as a parameter, copying slice memory address func D1 (s []int) {s[0] = 4 S[1] = 5 FMT. Println (s)}//pointer type passed, can achieve the purpose of modifying variable value func D2 (a *int) {*a = 2//Memory a value becomes 2 fmt. Println (*a)}/* output D----> [1 2]//slice [3 4]//slice 1 2//intd1----> [4 5 3]d2-- --2//parameter is pointer can modify variable value */ 

• Functions can also be used as a type

  package mainimport "fmt"func main() {    a := A //函数作为类型使用    a()}func A() {    fmt.Println("Func A")}//指针类型传递，可以达到修改变量值的目的/*输出a()---->    Func A*/

  The function name can be interpreted as the number of the memory address, which can be used to assign a value operation.

• anonymous function, different with the python language has a keyword lamada , go anonymous function explicit more straightforward, no function name, only need the Func keyword can
  Simply build an anonymous function, as follows

  // 匿名函数package mainimport "fmt"func main() {    a := func() { //没有函数名，直接进行赋值给变量        fmt.Println("Func A")    }    a() //调用匿名函数}

• Closure of a function: Also called a nested function, the returned type is a function, the function is assigned to the variable, re-passed to the parameter execution

  package mainimport "fmt"func main() {    f := closure(10)    fmt.Println(f(3))    fmt.Println(f(4))}func closure(x int) func(int) int { // 函数作为返回类型    return func(y int) int {        return x + y    }}/*输出f(3)--->    13f(4)--->    14*/