go语言渐入佳境[11]-function2

匿名函数

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package main

import (
"fmt"
"math"
)

//匿名函数
func main(){
//无参匿名函数
func(){
fmt.Println("jonson")
}()

//有参匿名函数
func(data int){
fmt.Println("data:",data)
}(5)

//有返回值的匿名函数
result:=func(data float64) float64{
return math.Sqrt(data)
}(9)

fmt.Println("result:",result)

//函数表达式
greet:=func(){
fmt.Println("greet jonson")
}
greet()

fmt.Printf("greet的类型是%T\n",greet)

闭包

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func greetjonson(){
x:=0

increment:= func() int{
x++
return x
}

fmt.Println(increment())
fmt.Println(increment())
}

函数作为返回值

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func makeGreeter() func() string{

return func() string {
return "hello jonson"
}
}

闭包与函数返回值

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func makeEvenGenerator() func() int{
i:=0
return func() int{
i+=2
return i
}
}

callback函数作为参数

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func visit(numbers []int,callback func(int)){

for _,n :=range numbers{
callback(n)
}
}

递归

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//  计算阶乘     5   5*4*3*2*1

func factorial(x uint) uint{

if x==0{
return 1
}
return x * factorial(x-1)
}

// factorial(5) //120
// returns: 5 * factorial(4)
// factorial(4) /24
// returns: 4 * factorial(3)
// factorial(3) //6
// returns: 3 * factorial(2)
// factorial(2) //2
// returns: 2 * factorial(1)
// factorial(1) //1
// returns: 1 * factorial(0)
// factorial(0)
// returns: 1

所有例子

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package main

import (
"fmt"
"math"
)

//匿名函数
func main(){
//无参匿名函数
func(){
fmt.Println("jonson")
}()

//有参匿名函数
func(data int){
fmt.Println("data:",data)
}(5)

//有返回值的匿名函数
result:=func(data float64) float64{
return math.Sqrt(data)
}(9)

fmt.Println("result:",result)


greet:=func(){
fmt.Println("greet jonson")
}
greet()

fmt.Printf("greet的类型是%T\n",greet)

//闭包
greetjonson()

//函数作为返回值

makejonson := makeGreeter()

fmt.Printf("类型:%T,返回值:%v\n",makejonson,makejonson())



//闭包做为返回值
makeeven := makeEvenGenerator()

fmt.Println("makeeven i = ",makeeven())
fmt.Println("makeeven i = ",makeeven())
fmt.Println("makeeven i = ",makeeven())

//callback函数作为参数
visit([]int{1,2,3,4},func(n int){
fmt.Println(n+1)
})

//死循环
fmt.Println(factorial(5))


var i uint = 0
for ;i<20;i++{

fmt.Println(fabicc(i))

}
}

//闭包


func greetjonson(){
x:=0

increment:= func() int{
x++
return x
}

fmt.Println(increment())
fmt.Println(increment())
}
//函数作为返回值

func makeGreeter() func() string{

return func() string {
return "hello jonson"
}
}


//闭包与函数返回值

func makeEvenGenerator() func() int{
i:=0
return func() int{
i+=2
return i
}
}


//callback函数作为参数

func visit(numbers []int,callback func(int)){

for _,n :=range numbers{
callback(n)
}
}


//递归

// 计算阶乘 5 5*4*3*2*1

func factorial(x uint) uint{

if x==0{
return 1
}
return x * factorial(x-1)
}

//fabicc


func fabicc(x uint) uint{

if(x==0){
return 0
}
if(x==1){
return 1
}

return fabicc(x-2) + fabicc(x-1)
}