How the Go language assigns values to the *int32 type

Directly on the code:

package mainimport "fmt"func main() {    var num *int32    var i int32 = 5    // 针对*int32的，先创建一个i类型，然后取i的地址，赋值给*int32    num = &i    fmt.Println("=====>:\t", num)    fmt.Println("=====>:\t", *num)}

Operation Result:

=====>:  0xc042064080=====>:  5Process finished with exit code 0

The following form is not possible:

package mainimport "fmt"func main() {    var num *int32    *num = 5    fmt.Println("=====>:\t", num)    fmt.Println("=====>:\t", *num)}

Operation Result:

panic: runtime error: invalid memory address or nil pointer dereference[signal 0xc0000005 code=0x1 addr=0x0 pc=0x48b4ea]goroutine 1 [running]:main.main()    E:/Program/go2/goPath/src/xingej-go/xingej-go/xingej-go666/string/test.go:7 +0x2aProcess finished with exit code 2  

Reason?
The address of the constant 5 may not be taken

How the Go language assigns values to the *int32 type