go语言的坑

• for-range

package main

import "fmt"

func main() {
	slice := []int{0, 1, 2, 3}
	mp := make(map[int]*int)
	fmt.Println("for range 坑")
	for index, value := range slice {
		mp[index] = &value
	}
	//根本原因在于for range是用一个变量承接mp中的内容的
	for key, value := range mp {
		fmt.Println(key, " ", *value)
	}

	fmt.Println("等价写法")
	var index, value int
	mp2 := make(map[int]*int)
	for index, value = range slice {
		mp2[index] = &value
	}

	for key, value := range mp2 {
		fmt.Println(key, " ", *value)
	}

	fmt.Println("正确写法")
	mp3 := make(map[int]*int)
	for index, value := range slice {
		num := value
		mp3[index] = &num
	}
	//根本原因在于for range是用一个变量承接mp中的内容的
	for key, value := range mp3 {
		fmt.Println(key, " ", *value)
	}

}

输出：

for range 坑
0   3
1   3
2   3
3   3
等价写法
0   3
1   3
2   3
3   3
正确写法
0   0
1   1
2   2
3   3