Golang如何使用指针打印结构值？

package main

import "fmt"

type A struct {
    a int32
    B *B
}
type B struct {
    b int32
}

func main() {
    a := &A{
        a: 1,
        B: &B{
            b: 2,
        },
    }
    fmt.Printf("v ==== %+v 
", a)
}


//ret: v ==== &{a:1 B:0xc42000e204}
//??? how to print B's content but not pointer

Basically, you have to do it yourself. There are two ways to do this. Either just print the thing how you want, or implement the Stringer interface for the struct by adding a func String() string, which gets called when you use the format %v. You could also reference each value in the format which is a struct.

Implementing the Stringer interface is the surest way to always get what you want. And you only have to do it once per struct, instead of per format string when you print.

https://play.golang.org/p/PKLcPFCqOe

package main

import "fmt"

type A struct {
    a int32
    B *B
}

type B struct{ b int32 }

func (aa *A) String() string {
    return fmt.Sprintf("A{a:%d, B:%v}",aa.a,aa.B)
}

func (bb *B) String() string {
    return fmt.Sprintf("B{b:%d}",bb.b)
}

func main() {
    a := &A{a: 1, B: &B{b: 2}}

    // using the Stringer interface
    fmt.Printf("v ==== %v 
", a)

    // or just print it yourself however you want.
    fmt.Printf("v ==== A{a:%d, B:B{b:%d}}
", a.a, a.B.b)

    // or just reference the values in the struct that are structs themselves
    // but this can get really deep
    fmt.Printf("v ==== A{a:%d, B:%v}", a.a, a.B)
}