关于Golang指针，为什么？

Question

What happened ?

var n interface{} = 2
var pn = &n
var pf = (*int64)(unsafe.Pointer(pn))
fmt.Println(pf)
fmt.Println(pn)
fmt.Println(*pn) // 2
fmt.Println(*pf) // not 2
*pf = 9
fmt.Println(*pn) //error invalid memory address or nil pointer dereference
fmt.Println(*pf) // 9

My question is Why is *pf not equal to *pn and error ?

Thanks for your reply.

Answer 1

1. n is of an interface{} type, so in memory it is represented by a struct of 2 values: a type and data. The type comes first. So you dereference it and interpret as a number.

2. *pf = 9 breaks that structure, so next time you try to dereference it - the runtime fails.