golang fmt格式化字符串%v,%T

T常用的格式化字符串有：

%v the value in a default format
when printing structs, the plus flag (%+v) adds field names
%#v a Go-syntax representation of the value
%T a Go-syntax representation of the type of the value

不同类型默认的%v 如下:

bool: %t
int, int8 etc.: %d
uint, uint8 etc.: %d, %#x if printed with %#v
float32, complex64, etc: %g
string: %s
chan: %p
pointer: %p

对于interface{}, %v会打印实际类型的值。
举例说明如下。

example

package main

import (

        "fmt"
)


type Power struct{
        age int
        high int
        name string
}

func main() {

        var i Power = Power{age: 10, high: 178, name: "NewMan"}

        fmt.Printf("type:%T\n", i)
        fmt.Printf("value:%v\n", i)
        fmt.Printf("value+:%+v\n", i)
        fmt.Printf("value#:%#v\n", i)


        fmt.Println("========interface========")
        var interf interface{} = i
        fmt.Printf("%v\n", interf)
        fmt.Println(interf)
}

•  

output:

type:main.Power
value:{10 178 NewMan}
value+:{age:10 high:178 name:NewMan}
value#:main.Power{age:10, high:178, name:”NewMan”}
========interface========
{10 178 NewMan}
{10 178 NewMan}