package main

import (
    "fmt"
    "encoding/hex"
)

func main() {
    // 注意"Hello"與"encodedStr"不相等，encodedStr是用字符串來表示16進(jìn)制
    src := []byte("Hello")
    encodedStr := hex.EncodeToString(src)
    // [72 101 108 108 111]
    fmt.Println(src)
    // 48656c6c6f -> 48(4*16+8=72) 65(6*16+5=101) 6c 6c 6f 
    fmt.Println(encodedStr)
}

test, _ := hex.DecodeString(encodedStr)
fmt.Println(bytes.Compare(test, src)) // 0

type stringStruct struct {
    str unsafe.Pointer
    len int
}

func gostringnocopy(str *byte) string {
	ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
	s := *(*string)(unsafe.Pointer(&ss))
	return s
}

type slice struct {
	array unsafe.Pointer
	len   int
	cap   int
}

s := "A1" // 分配存儲"A1"的內(nèi)存空間，s結(jié)構(gòu)體里的str指針指向這快內(nèi)存
s = "A2"  // 重新給"A2"的分配內(nèi)存空間，s結(jié)構(gòu)體里的str指針指向這快內(nèi)存

s := []byte{1} // 分配存儲1數(shù)組的內(nèi)存空間，s結(jié)構(gòu)體的array指針指向這個數(shù)組。
s = []byte{2}  // 將array的內(nèi)容改為2

func stringtoslicebyte(buf *tmpBuf, s string) []byte {
	var b []byte
	if buf != nil && len(s) <= len(buf) {
		*buf = tmpBuf{}
		b = buf[:len(s)]
	} else {
		b = rawbyteslice(len(s))
	}
	copy(b, s)
	return b
}
 
func rawstring(size int) (s string, b []byte) {
	p := mallocgc(uintptr(size), nil, false)
 
	stringStructOf(&s).str = p
	stringStructOf(&s).len = size
 
	*(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
 
	return
}

func slicebytetostring(buf *tmpBuf, b []byte) string {
	l := len(b)
	if l == 0 {
		// Turns out to be a relatively common case.
		// Consider that you want to parse out data between parens in "foo()bar",
		// you find the indices and convert the subslice to string.
		return ""
	}
	if raceenabled && l > 0 {
		racereadrangepc(unsafe.Pointer(&b[0]),
			uintptr(l),
			getcallerpc(unsafe.Pointer(&buf)),
			funcPC(slicebytetostring))
	}
	if msanenabled && l > 0 {
		msanread(unsafe.Pointer(&b[0]), uintptr(l))
	}
	s, c := rawstringtmp(buf, l)
	copy(c, b)
	return s
}
 
func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
	if buf != nil && l <= len(buf) {
		b = buf[:l]
		s = slicebytetostringtmp(b)
	} else {
		s, b = rawstring(l)
	}
	return
}

package string_slicebyte_test
 
import (
	"log"
	"reflect"
	"testing"
	"unsafe"
)
 
func stringtoslicebyte(s string) []byte {
	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
	bh := reflect.SliceHeader{
		Data: sh.Data,
		Len:  sh.Len,
		Cap:  sh.Len,
	}
	return *(*[]byte)(unsafe.Pointer(&bh))
}
 
func slicebytetostring(b []byte) string {
	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
	sh := reflect.StringHeader{
		Data: bh.Data,
		Len:  bh.Len,
	}
	return *(*string)(unsafe.Pointer(&sh))
}
 
func TestStringSliceByte(t *testing.T) {
	s1 := "abc"
	b1 := []byte("def")
	copy(b1, s1)
	log.Println(s1, b1)
 
	s := "hello"
	b2 := stringtoslicebyte(s)
	log.Println(b2)
    // b2[0] = byte(99) unexpected fault address
 
	b3 := []byte("test")
	s3 := slicebytetostring(b3)
	log.Println(s3)
}