package main

import (
	"encoding/json"
	"fmt"
)

type object struct {
	Num int  `json:"num"`
	Ptr *int `json:"ptr"`
}

func main() {
	var obj object
	var Inum = `{"num": null, "ptr": null}`
	
	json.Unmarshal([]byte(Inum), &obj)
	fmt.Printf("%#v\n", obj)
}