golang learning ---- nil value

The null golang

Two null values ​​are not comparable

func main() {
    fmt.Println(nil==nil)
}

Operating results shown below:

nil is not the default type

func main() {
    fmt.Printf("%T", nil)
    print(nil)
}

Operating results shown below:

Different types of pointers are the same nil

func main() {
    var m map[int]string
    var num *int
    fmt.Printf("%p\n", m)
    fmt.Printf("%p", num)
}

Operating results shown below:

map, slice, pointer channel func, a zero value,, interface is nil

func main() {
    var m map[int]string
    var ptr *int
    var c chan int
    var sl []int
    var f func()
    var i interface{}
    var k struct{
        name string
        age int
    }
    fmt.Printf("%#v\n", m)
    fmt.Printf("%#v\n", ptr)
    fmt.Printf("%#v\n", c)
    fmt.Printf("%#v\n", sl)
    fmt.Printf("%#v\n", f)
    fmt.Printf("%#v\n", i)
    fmt.Printf("%#v\n",k)
}

FIG results are as follows:

Different types of nil value memory size may not be the same

func main() {
    var p *struct{}
    fmt.Println( unsafe.Sizeof( p ) ) // 8
    var s []int
    fmt.Println( unsafe.Sizeof( s ) ) // 24
    var m map[int]bool
    fmt.Println( unsafe.Sizeof( m ) ) // 8
    var c chan string
    fmt.Println( unsafe.Sizeof( c ) ) // 8
    var f func()
    fmt.Println( unsafe.Sizeof( f ) ) // 8
    var i interface{}
    fmt.Println( unsafe.Sizeof( i ) ) // 16
}

FIG results are as follows: