英文:
How to read a binary file into a struct and reflection - Go Language
问题
我正在尝试编写一个程序，将二进制文件读入到Golang中的结构体中。我的方法是使用binary包读取二进制文件，并将其填充到包含数组的结构体中。我使用数组而不是切片，因为我想指定字段的长度。这似乎工作得很好，但是当我尝试使用反射打印字段的值时，出现了以下错误：
panic: reflect: call of reflect.Value.Bytes on array Value
以下是代码：
package main
import (
"encoding/binary"
"fmt"
"log"
"os"
"reflect"
)
type SomeStruct struct {
Field1 [4]byte
Field2 [2]byte
Field3 [1]byte
}
func main() {
f, err := os.Open("/Users/user/Downloads/file.bin")
if err != nil {
log.Fatalln(err)
}
defer f.Close()
s := SomeStruct{}
err = binary.Read(f, binary.LittleEndian, &s)
numOfFields := reflect.TypeOf(s).NumField()
ps := reflect.ValueOf(&s).Elem()
for i := 0; i < numOfFields; i++ {
value := ps.Field(i).Bytes()
for j := 0; j < len(value); j++ {
fmt.Print(value[j])
}
}
}
当我将代码更改为以下内容时：
package main
import (
"encoding/binary"
"fmt"
"log"
"os"
"reflect"
)
type SomeStruct struct {
Field1 [4]byte
Field2 [2]byte
Field3 [1]byte
}
func main() {
f, err := os.Open("/Users/user/Downloads/file.bin")
if err != nil {
log.Fatalln(err)
}
defer f.Close()
s := SomeStruct{}
err = binary.Read(f, binary.LittleEndian, &s)
numOfFields := reflect.TypeOf(s).NumField()
ps := reflect.ValueOf(&s).Elem()
for i := 0; i < numOfFields; i++ {
value := ps.Field(i)
fmt.Print(value)
}
}
它会打印出数组的ASCII表示形式，我需要打印ASCII的字符表示形式，这就是我遇到panic的原因。
你有什么想法吗？
英文:
I am trying to write a program to read a binary file into a struct in golang, the approach is to use the binary package to read a binary file to populate a struct that contains arrays, I am using arrays and not slices because I want to specify the field length, this seems to work fine but when I try to use reflection to print our the values of the fields I am getting this error
panic: reflect: call of reflect.Value.Bytes on array Value
Here is the code
package main
import (
"encoding/binary"
"fmt"
"log"
"os"
"reflect"
)
type SomeStruct struct {
Field1 [4]byte
Field2 [2]byte
Field3 [1]byte
}
func main() {
f, err := os.Open("/Users/user/Downloads/file.bin")
if err != nil {
log.Fatalln(err)
}
defer f.Close()
s := SomeStruct{}
err = binary.Read(f, binary.LittleEndian, &s)
numOfFields := reflect.TypeOf(s).NumField()
ps := reflect.ValueOf(&s).Elem()
for i := 0; i < numOfFields; i++ {
value := ps.Field(i).Bytes()
for j := 0; j < len(value); j++ {
fmt.Print(value[j])
}
}
}
when I change the code to this
package main
import (
"encoding/binary"
"fmt"
"log"
"os"
"reflect"
)
type SomeStruct struct {
Field1 [4]byte
Field2 [2]byte
Field3 [1]byte
}
func main() {
f, err := os.Open("/Users/user/Downloads/file.bin")
if err != nil {
log.Fatalln(err)
}
defer f.Close()
s := SomeStruct{}
err = binary.Read(f, binary.LittleEndian, &s)
numOfFields := reflect.TypeOf(s).NumField()
ps := reflect.ValueOf(&s).Elem()
for i := 0; i < numOfFields; i++ {
value := ps.Field(i)
fmt.Print(value)
}
}
it prints the arrays with their ascii representation, I need to print the char representation of the ascii and that when I get the panic
thoughts?
答案1
得分: 2
Bytes 文档中提到：
Bytes 返回 v 的底层值。如果 v 的底层值不是一个字节切片，则会引发 panic。
将数组切片化以获取字节切片：
field := ps.Field(i)
value := field.Slice(0, field.Len()).Bytes()
for j := 0; j < len(value); j++ {
fmt.Print(value[j])
}
你也可以通过迭代数组来实现：
value := ps.Field(i)
for j := 0; j < value.Len(); j++ {
fmt.Print(byte(value.Index(j).Uint()))
}
英文:
The Bytes documentation says:
> Bytes returns v's underlying value. It panics if v's underlying value is not a slice of bytes.
Slice the array to get a slice of bytes:
field := ps.Field(i)
value := field.Slice(0, field.Len()).Bytes()
for j := 0; j < len(value); j++ {
fmt.Print(value[j])
}
You can also iterate through the array:
value := ps.Field(i)
for j := 0; j < value.Len(); j++ {
fmt.Print(byte(value.Index(j).Uint()))
}
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