Golang: How to printf % x for bytes in a struct?

huangapple
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英文:

Golang: How to printf % x for bytes in a struct?

问题

以下是翻译的内容：

  1. var b [88]byte
  2. n, err := file.Read(b[:])
  3. fmt.Printf("读取的字节数：%d 字节：[% x]\n", n, b)
  5. 上述代码以十六进制打印字节
  7. 我有一个如下的结构体
  9.     type SomeStruct struct {
  10.        field1 []byte
  11.        field2 []byte
  12.     }
  13.     someStructInstance := SomeStruct{[249 190 180 217], [29 1 0 0]}
  14.     fmt.Println(someStructInstance)
  15.     => {[249 190 180 217] [29 1 0 0]}
  16.    
  17. 但是我希望它以十六进制打印
  19.     => {[f9 be b4 d9] [1d 01 00 00]}
  21. 我该如何实现这个目标？
英文: 
  1. var b [88]byte
  2. n, err := file.Read(b[:])
  3. fmt.Printf("bytes read: %d Bytes: [% x]\n", n, b)

The above prints bytes in hexdecimal

I have a struct like this

  1. type SomeStruct struct {
  2.    field1 []byte
  3.    field2 []byte
  4. }
  5. someStructInstance := SomeStruct{[249 190 180 217], [29 1 0 0]}
  6. fmt.Println(someStructInstance)
  7. => {[249 190 180 217] [29 1 0 0]}

But ideally I would like it to print hexdecimal

  1. => {[f9 be b4 d9] [1d 01 00 00]}

How would I go about that?

答案1

得分: 5

我认为你只需要在SomeStruct上定义自己的String函数。这是一个示例：

  1. package main
  3. import "fmt"
  5. type SomeStruct struct {
  6.    field1 []byte
  7.    field2 []byte
  8. }
  10. func (s SomeStruct) String() string {
  11.   return fmt.Sprintf("{[% x] [% x]}", s.field1, s.field2)
  12. }
  14. func main() {
  15.   someStructInstance := SomeStruct{[]byte{249, 190, 180, 217}, []byte{29, 1, 0, 0}}
  16.   fmt.Println(someStructInstance)
  17. }

在Go Playground上运行它：http://play.golang.org/p/eYBa1n33a2

英文:

I think you will just have to define your own String function on SomeStruct. Here is an example:

  1. package main
  3. import "fmt"
  5. type SomeStruct struct {
  6.    field1 []byte
  7.    field2 []byte
  8. }
  10. func (s SomeStruct) String() string {
  11.   return fmt.Sprintf("{[% x] [% x]}", s.field1, s.field2)
  12. }
  14. func main() {
  15.   someStructInstance := SomeStruct{[]byte{249, 190, 180, 217}, []byte{29, 1, 0, 0}}
  16.   fmt.Println(someStructInstance)
  17. }

See it in running on the Go Playground: http://play.golang.org/p/eYBa1n33a2

答案2

得分: 3

你可以使用反射来检查结构体并打印其中的任何[]byte。

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"reflect"
  6. )
  8. type SomeStruct struct {
  9. 	field1 []byte
  10. 	field2 []byte
  11. }
  13. type OtherStruct struct {
  14. 	intValue  int
  15. 	intSlice  []int
  16. 	byteSlice []byte
  17. }
  19. var typeOfBytes = reflect.TypeOf([]byte(nil))
  21. func printSlicesHex(obj interface{}) {
  22. 	value := reflect.ValueOf(obj)
  23. 	typeOfObj := value.Type()
  24. 	for i := 0; i < value.NumField(); i++ {
  25. 		field := value.Field(i)
  26. 		if field.Type() == typeOfBytes {
  27. 			bytes := field.Bytes()
  28. 			printBytes(typeOfObj.Field(i).Name, bytes)
  29. 		}
  30. 	}
  31. }
  33. func printBytes(name string, bytes []byte) {
  34. 	fmt.Printf("%s: [% x]\n", name, bytes)
  35. }
  37. func main() {
  38. 	someStructInstance := SomeStruct{[]byte{249, 190, 180, 217}, []byte{29, 1, 0, 0}}
  39. 	fmt.Println("Printing []bytes in SomeStruct")
  40. 	printSlicesHex(someStructInstance)
  41. 	fmt.Println()
  43. 	otherStruct := OtherStruct{0, []int{0, 1, 2}, []byte{0, 1, 2, 3}}
  44. 	fmt.Println("Printing []bytes in OtherStruct")
  45. 	printSlicesHex(otherStruct)
  46. }

这个示例会打印每个[]byte字段的名称和数据（以十六进制形式）。你可以通过传入一个自定义函数来改进它，以便不总是以十六进制形式打印。

Playground链接

英文:

You could use reflection to inspect the struct and print any []bytes that it has.

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;reflect&quot;
  6. )
  8. type SomeStruct struct {
  9. 	field1 []byte
  10. 	field2 []byte
  11. }
  13. type OtherStruct struct {
  14. 	intValue  int
  15. 	intSlice  []int
  16. 	byteSlice []byte
  17. }
  19. var typeOfBytes = reflect.TypeOf([]byte(nil))
  21. func printSlicesHex(obj interface{}) {
  22. 	value := reflect.ValueOf(obj)
  23. 	typeOfObj := value.Type()
  24. 	for i := 0; i &lt; value.NumField(); i++ {
  25. 		field := value.Field(i)
  26. 		if field.Type() == typeOfBytes {
  27. 			bytes := field.Bytes()
  28. 			printBytes(typeOfObj.Field(i).Name, bytes)
  29. 		}
  30. 	}
  31. }
  33. func printBytes(name string, bytes []byte) {
  34. 	fmt.Printf(&quot;%s: [% x]\n&quot;, name, bytes)
  35. }
  37. func main() {
  38. 	someStructInstance := SomeStruct{[]byte{249, 190, 180, 217}, []byte{29, 1, 0, 0}}
  39. 	fmt.Println(&quot;Printing []bytes in SomeStruct&quot;)
  40. 	printSlicesHex(someStructInstance)
  41. 	fmt.Println()
  43. 	otherStruct := OtherStruct{0, []int{0, 1, 2}, []byte{0, 1, 2, 3}}
  44. 	fmt.Println(&quot;Printing []bytes in OtherStruct&quot;)
  45. 	printSlicesHex(otherStruct)
  46. }

For each []byte, this example prints the name of the field and its data (in hex). You could improve on this by taking a custom function to do the printing, so you don't always have to print in hex.

Playground Link

huangapple
  • 本文由 发表于 2014年1月6日 06:23:21
  • 转载请务必保留本文链接：https://go.coder-hub.com/20939998.html
  • byte
  • go
  • printf
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