The use of go unsafe

Explain not to arrange pointers for ：

　　unsafe.Pointer In fact, it's similar C Of void *, stay golang Is used for a variety of pointer conversion bridge .uintptr yes golang Built in type , It's an integer that can store pointers ,uintptr The bottom type of is int, It and unsafe.Pointer Can be converted to each other .

　　 Under normal circumstances go Structure private variables in a language cannot be accessed or modified directly , But it can go through unsafe To directly access or modify any variable

package main
 
import (
	_ "ORMTest/routers"
	"fmt"
	"unsafe"
)
 
func main() {
	d := struct {
		s string
		i int
	}{"abc", 100}
	p := uintptr(unsafe.Pointer(&d)) // *struct -> Pointer -> uintptr
	p += unsafe.Offsetof(d.s)        // uintptr + offset
 
	p2 := unsafe.Pointer(p) // uintptr -> Pointer
	px := (*int)(p2)        // Pointer -> *int
	*px = 200               // d.s = 200
	fmt.Printf("%#v\n", d)
}

Output ：

{s string;x int}{s:"abc",x:200}