了解界面

Question

I am a newbie in Go lang , I was trying to understand Go Interface by writing a simple piece of code . I am getting an error , as I am not able to understand the correct way of referring to a Interface method kindly tell me where I am going wrong.

type Info interface {
Noofchar() int
}

type Testinfo struct {
noofchar int
}

func (x Testinfo)Noofchar() int {
return x.noofchar
}

func main(){
var t Info
fmt.Println(x.Testinfo)
fmt.Println("No of char ",t.Noofchar())
x.noofchar++
fmt.Println("No of char ",t.Noofchar())
}

Am I referring to the method correctly by t.Noofchar() ? or there is something else that I am missing

Answer 1

x is a variable to which you can assign anything that implements the Info interface. You've assigned nothing to that variable.

Once you assign something, x.noofchar++ will not work because again x can hold anything that implements the Info interface, which means you can only access the methods defined by that interface. Interfaces do not allow direct access to fields.

The only method defined in the Info interface is the Noofchar() int method, so that is the only way to interact with the value stored in x.

The x defined by the method receiver (x Testinfo) isn't at all related to the var x Info variable. That x does have direct access to the struct fields.

The t.Noofchar() calls are correct and will work.