unsafe.Pointer 和 uintptr

前言

unsafe.Pointer 是一个万能指针类型，对应c语言中的 void *

unitptr 是一个整数类型，可以进行算术运算

若想要对指针指向的值进行修改，必须转换为uintptr类型，再强转为 （指针）（unsafe.Pointer（））

例子

func main() {
	a:=[4]int{0,1,2,3}
	p1:=unsafe.Pointer(&a[1])
	p3:=uintptr(p1)+2*unsafe.Sizeof(a[0])
	*(*int)(unsafe.Pointer(p3))=6
	fmt.Println(a)

//------
    type Person struct {
	name   string
	age    int
	gender bool
    }

    who := Person{"John", 30, true}
    pp := unsafe.Pointer(&who)
    pname := (*string)(unsafe.Pointer(uintptr(pp) + unsafe.Offsetof(who.name)))
    page := (*int)(unsafe.Pointer(uintptr(pp) + unsafe.Offsetof(who.age)))
    pgender := (*bool)(unsafe.Pointer(uintptr(pp) + unsafe.Offsetof(who.gender)))
    *pname = "Alice"
    *page = 28
    *pgender = false
    fmt.Println(who) // {Alice 28 false}
}