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Which values ​​are not addressable in Golang

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(*-*)浩Original
2019-12-17 13:44:433898browse

Which values ​​are not addressable in Golang

cannot be addressed, which means that its address cannot be obtained through &. (Recommended Learning: Go )

# 不 can be summarized as: non -changing, temporary results and unsafe. If any of these conditions are met, it is not addressable.

Specifically:

package main    
type Named interface {    
	// Name 用于获取名字。    
	Name() string    
}    
type Dog struct {    
	name string    
}    
func (dog *Dog) SetName(name string) {    
	dog.name = name    
}    
func (dog Dog) Name() string {    
	return dog.name    
}    
func main() {    
	// 示例1。    
	const num = 123    
	//_ = &num // 常量不可寻址。    
	//_ = &(123) // 基本类型值的字面量不可寻址。    
	var str = "abc"    
	_ = str    
	//_ = &(str[0]) // 对字符串变量的索引结果值不可寻址。    
	//_ = &(str[0:2]) // 对字符串变量的切片结果值不可寻址。    
	str2 := str[0]    
	_ = &str2 // 但这样的寻址就是合法的。    
	//_ = &(123 + 456) // 算术操作的结果值不可寻址。    
	num2 := 456    
	_ = num2    
	//_ = &(num + num2) // 算术操作的结果值不可寻址。    
	//_ = &([3]int{1, 2, 3}[0]) // 对数组字面量的索引结果值不可寻址。    
	//_ = &([3]int{1, 2, 3}[0:2]) // 对数组字面量的切片结果值不可寻址。    
	_ = &([]int{1, 2, 3}[0]) // 对切片字面量的索引结果值却是可寻址的。    
	//_ = &([]int{1, 2, 3}[0:2]) // 对切片字面量的切片结果值不可寻址。    
	//_ = &(map[int]string{1: "a"}[0]) // 对字典字面量的索引结果值不可寻址。    
	var map1 = map[int]string{1: "a", 2: "b", 3: "c"}    
	_ = map1    
	//_ = &(map1[2]) // 对字典变量的索引结果值不可寻址。    
	//_ = &(func(x, y int) int {    
	//	return x + y    
	//}) // 字面量代表的函数不可寻址。    
	//_ = &(fmt.Sprintf) // 标识符代表的函数不可寻址。    
	//_ = &(fmt.Sprintln("abc")) // 对函数的调用结果值不可寻址。    
	dog := Dog{"little pig"}    
	_ = dog    
	//_ = &(dog.Name) // 标识符代表的函数不可寻址。    
	//_ = &(dog.Name()) // 对方法的调用结果值不可寻址。    
	//_ = &(Dog{"little pig"}.name) // 结构体字面量的字段不可寻址。    
	//_ = &(interface{}(dog)) // 类型转换表达式的结果值不可寻址。    
	dogI := interface{}(dog)    
	_ = dogI    
	//_ = &(dogI.(Named)) // 类型断言表达式的结果值不可寻址。    
	named := dogI.(Named)    
	_ = named    
	//_ = &(named.(Dog)) // 类型断言表达式的结果值不可寻址。    
	var chan1 = make(chan int, 1)    
	chan1 <- 1    
	//_ = &(<-chan1) // 接收表达式的结果值不可寻址。    
}

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