可以将接口用作动态变量吗？

huangapple
go评论108阅读模式
英文:

Can I use interfaces as dynamic variables?

问题

Go语言不支持动态变量。

话虽如此，我想知道下面这个程序中变量"a"是什么，因为我可以将其用作整数和字符串。甚至条件语句也可以正常使用。

  1. package main
  3. import (
  4. 	"fmt"
  5. )
  7. func main() {
  8. 	var a interface{}
  9. 	myInt := 1
  10. 	myString := "hi"
  11. 	
  12. 	a = myInt
  13. 	if a == 1 {
  14. 		fmt.Println("equals to 1")
  15. 	}
  16. 	
  17. 	a = myString
  18. 	if a == "hi" {
  19. 		fmt.Println(a)
  20. 	}
  21. }
英文:

Go doesn't have dynamic variables.

That said, I would like to know what the variable "a" is, in this program bellow, once I can use it as integer and as string. Even conditionals statements work well with it

  1. package main
  3. import (
  4. 	"fmt"
  5. )
  7. func main() {
  8. 	var a interface{}
  9. 	myInt := 1
  10. 	myString := "hi"
  11. 	
  12. 	a = myInt
  13. 	if a == 1 {
  14. 		fmt.Println("equals to 1")
  15. 	}
  16. 	
  17. 	a = myString
  18. 	if a == "hi" {
  19. 		fmt.Println(a)
  20. 	}
  21. }

答案1

得分: 4

你可以使用类型开关（type switch）：

  1. package main
  3. func main() {
  4.    var a interface{} = 1
  6.    switch aType := a.(type) {
  7.    case string:
  8.       println("string", aType)
  9.    case int:
  10.       println("int", aType)
  11.    }
  12. }

https://golang.org/ref/spec#Type_switches

英文:

You can use a type switch:

  1. package main
  3. func main() {
  4.    var a interface{} = 1
  6.    switch aType := a.(type) {
  7.    case string:
  8.       println("string", aType)
  9.    case int:
  10.       println("int", aType)
  11.    }
  12. }

<https://golang.org/ref/spec#Type_switches>

答案2

得分: 1

要确定变量'a'的类型，可以使用reflect.TypeOf()函数。我重新创建了你的代码如下：

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"reflect"
  6. )
  8. func main() {
  9. 	var a interface{}
  10. 	myInt := 1
  11. 	myString := "hi"
  13. 	a = myInt
  14. 	if a == 1 {
  15. 		fmt.Println("equals to 1")
  16. 		fmt.Println(reflect.TypeOf(a))
  17. 	}
  19. 	a = myString
  20. 	if a == "hi" {
  21. 		fmt.Println(a)
  22. 		fmt.Println(reflect.TypeOf(a))
  23. 	}
  24. }

输出结果：

  1. equals to 1
  2. int
  3. hi
  4. string
英文:

To determine what the variable type of 'a' you can make use of reflect.TypeOf(),I recreated your code as follows:

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;reflect&quot;
  6. )
  8. func main() {
  9. 	var a interface{}
  10. 	myInt := 1
  11. 	myString := &quot;hi&quot;
  13. 	a = myInt
  14. 	if a == 1 {
  15. 		fmt.Println(&quot;equals to 1&quot;)
  16. 		fmt.Println(reflect.TypeOf(a))
  17. 	}
  19. 	a = myString
  20. 	if a == &quot;hi&quot; {
  21. 		fmt.Println(a)
  22. 		fmt.Println(reflect.TypeOf(a))
  23. 	}
  24. }

Output:

  1. equals to 1
  2. int
  3. hi
  4. string

huangapple
  • 本文由 发表于 2021年6月30日 08:49:49
  • 转载请务必保留本文链接：https://go.coder-hub.com/68187230.html
  • go
  • variables
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