go语言渐入佳境[11]-function2-创新互联

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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)

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func greetjonson(){
	x:=0

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

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

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func makeGreeter() func() string{

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

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

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

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

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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

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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)
}