1

我想将结构的值复制到 uint64，没有不安全的正确方法是什么？

package main

import "fmt"

type T struct {
    id [7]byte
    no uint8
}

func main() {
    t1 := T{[7]byte{'A', 'B', 'C', 'D', 'E', 'F', 'G'}, 7}
    var u uint64

    //TODO: copy t1's content into u (both id and no)
    //u = *((*uint64)(unsafe.Pointer(&t1)))

    fmt.Println(t1, u)
}
4

2 回答 2

2

你尝试过类型转换吗？

u = uint64(t1.no)

喔好吧。你试过 binary.Write / binary.Read 吗？

package main

import (
    "bytes"
    "encoding/binary"
    "fmt"
)

type T struct {
    id [7]byte
    no uint8
}

func main() {
    t1 := T{[7]byte{'A', 'B', 'C', 'D', 'E', 'F', 'G'}, 7}
    var u uint64

    var b bytes.Buffer
    binary.Write(&b, binary.LittleEndian, &t1)
    binary.Read(&b, binary.LittleEndian, &u)

    fmt.Println(t1, u)
}

但是，注意二进制包使用反射包，反射包使用不安全包。

于 2013-06-17T03:06:43.333 回答
2

例如，在 little-endian 架构上，不使用 package unsafe，

package main

import (
    "fmt"
    "unsafe"
)

type T struct {
    id [7]byte
    no uint8
}

func Uint64LEFromT(t T) uint64 {
    return uint64(t.id[0]) | uint64(t.id[1])<<8 | uint64(t.id[2])<<16 | uint64(t.id[3])<<24 |
        uint64(t.id[4])<<32 | uint64(t.id[5])<<40 | uint64(t.id[6])<<48 | uint64(t.no)<<56
}

func Uint64LEToT(t *T, v uint64) {
    t.id[0] = byte(v)
    t.id[1] = byte(v >> 8)
    t.id[2] = byte(v >> 16)
    t.id[3] = byte(v >> 24)
    t.id[4] = byte(v >> 32)
    t.id[5] = byte(v >> 40)
    t.id[6] = byte(v >> 48)
    t.no = byte(v >> 56)
}

func main() {
    t1, t2 := T{[7]byte{'A', 'B', 'C', 'D', 'E', 'F', 'G'}, 7}, T{}
    var u1, u2 uint64

    //TODO: copy t1's content into u1 (both id and no)
    u1 = *((*uint64)(unsafe.Pointer(&t1)))
    fmt.Printf("t1 to u1 (unsafe): t1 %X u1 %X\n", t1, u1)

    //DONE:
    u2 = Uint64LEFromT(t1)
    fmt.Printf("t1 to u2 (safe):   t1 %X u2 %X\n", t1, u2)
    Uint64LEToT(&t2, u2)
    fmt.Printf("u2 to t2 (safe):   t2 %X u2 %X\n", t2, u2)
}

输出：

t1 to u1 (unsafe): t1 {41424344454647 7} u1 747464544434241
t1 to u2 (safe):   t1 {41424344454647 7} u2 747464544434241
u2 to t2 (safe):   t2 {41424344454647 7} u2 747464544434241
于 2013-06-17T06:34:52.333 回答