英文:
trying to insert integer into byte array
问题
我有一个字节数组：
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
我想知道如何用包含 300 的两个字节替换 app0[13:15]。
请帮忙。我尝试了以下代码，但它甚至无法编译通过：
app0[13:15] = []byte(300)
英文:
I have an array of bytes
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
I am trying to figure out how to replace app0[13:15] with two bytes containing 300.
Please help. I tried the following but it won't even compile:
app0[13:15] = []byte(300)
答案1
得分: 1
我有点困惑，你到底想用这段代码做什么？
app0[13:15] = []byte(300)
一个字节无法存储数值300，而且你有一个字节切片。我猜你想将数值300转换为两个字节：
import (
"fmt"
"bytes"
"encoding/binary"
)
func main() {
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
app0 = append(app0[:13], append(intToBytes(uint16(300)), app0[15:]...)...)
fmt.Println(app0)
}
func intToBytes(i uint16) []byte {
buf := new(bytes.Buffer)
_ = binary.Write(buf, binary.LittleEndian, i)
return buf.Bytes()
}
这里的技巧是你必须先获取一个字节数组，然后使用可变参数运算符（...）和append函数来替换数组的内部元素。
英文:
I'm a little confused what you are even trying to do with
app0[13:15] = []byte(300)
A single byte can't hold the value 300, and you have a slice of bytes. I'll assume you want the value 300 converted into two bytes:
import (
"fmt"
"bytes"
"encoding/binary"
)
func main() {
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
app0 = append(app0[:13], append(intToBytes(uint16(300)), app0[15:]...)...)
fmt.Println(app0)
}
func intToBytes(i uint16) []byte {
buf := new(bytes.Buffer)
_ = binary.Write(buf, binary.LittleEndian, i)
return buf.Bytes()
}
https://play.golang.org/p/qADHwCCFQG
The trick here is you have to actually get an array of bytes, and then you can use the variadic operator (...) and then append function to replace the inner elements of the array.
答案2
得分: 1
例如，
package main
import "fmt"
func main() {
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
fmt.Println(app0)
app0[13], app0[14] = 300>>8, 300&0xFF
fmt.Println(app0)
}
输出：
[255 224 0 16 74 70 73 70 0 1 1 1 0 0 0 0 0 0]
[255 224 0 16 74 70 73 70 0 1 1 1 0 1 44 0 0 0]
英文:
For example,
package main
import "fmt"
func main() {
app0 := []byte("\xff\xe0\x00\x10\x4a\x46\x49\x46\x00\x01\x01\x01\x00\x00\x00\x00\x00\x00")
fmt.Println(app0)
app0[13], app0[14] = 300>>8, 300&0xFF
fmt.Println(app0)
}
Output:
[255 224 0 16 74 70 73 70 0 1 1 1 0 0 0 0 0 0]
[255 224 0 16 74 70 73 70 0 1 1 1 0 1 44 0 0 0]
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