Go奇技淫巧

string的本质：reflect.StringHeader{}
slice的本质：reflect.SliceHeader{}
go指针的本质：unsafe.Pointer{}、uintptr{}

获取slice和string的内存地址####

func stringPointer(s string) unsafe.Pointer {
  // string的指针本质是*reflect.StringHeader
  p := (*reflect.StringHeader)(unsafe.Pointer(&s))
  return unsafe.Pointer(p.Data)
}

func bytePointer(b []byte) unsafe.Pointer {
   // slice的指针本质是*reflect.SliceHeader
  p := (*reflect.SliceHeader)(unsafe.Pointer(&b))
  return unsafe.Pointer(p.Data)
}```

####把[]byte转成string####
类型转换：string(b)，为了稳定性Go内部进行了数据复制。
为了获的更好的性能，我们可以这样：

func byteString(b []byte) string {
// reflect.StringHeader和reflect.SliceHeader的结构体相似
return (string)(unsafe.Pointer(&b))
}```

结构体和[]byte互转####

type MyStruct struct {
    A int
    B int
}

var sizeOfMyStruct = int(unsafe.Sizeof(MyStruct{}))

func MyStructToBytes(s *MyStruct) []byte {
    var x reflect.SliceHeader
    x.Len = sizeOfMyStruct
    x.Cap = sizeOfMyStruct
    x.Data = uintptr(unsafe.Pointer(s))
    return *(*[]byte)(unsafe.Pointer(&x))
}

func BytesToMyStruct(b []byte) *MyStruct {
    return (*MyStruct)(unsafe.Pointer(
        (*reflect.SliceHeader)(unsafe.Pointer(&b)).Data,
    ))
}```
这种方式同样也适用于string与[]byte互转:

var sizeOfString = int(unsafe.Sizeof(""))

func StringtToBytes(s *string) []byte {
var x reflect.SliceHeader
x.Len = sizeOfMyStruct
x.Cap = sizeOfMyStruct
x.Data = uintptr(unsafe.Pointer(s))
return ([]byte)(unsafe.Pointer(&x))
}

func BytesToString(b []byte) string{
return (string)(unsafe.Pointer(
(*reflect.SliceHeader)(unsafe.Pointer(&b)).Data,
))
}```