dqy27359
2017-01-05 08:43
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已采纳

如何使Go将枚举字段打印为字符串?

You print an enum that implements Stringer using "%v", it will print its string value. If you declare the same enum inside a struct and print the struct using "%v", it will print enum's numeric value. Is there a way to print the string value of a enum field?

Sample (https://play.golang.org/p/AP_tzzAZMI):

package main

import (
    "fmt"
)

type MyEnum int

const (
    Foo MyEnum = 1
    Bar MyEnum = 2
)

func (e MyEnum) String() string {
    switch e {
    case Foo:
        return "Foo"
    case Bar:
        return "Bar"
    default:
        return fmt.Sprintf("%d", int(e))
    }
}

type MyStruct struct {
    field MyEnum
}

func main() {
    info := &MyStruct{
        field: MyEnum(1),
    }
    fmt.Printf("%v
", MyEnum(1))
    fmt.Printf("%v
", info)
    fmt.Printf("%+v
", info)
    fmt.Printf("%#v
", info)
}

Prints:

Foo
&{1}
&{field:1}
&main.MyStruct{field:1}
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1条回答 默认 最新

  • duanlu1922 2017-01-05 08:51
    已采纳

    You need to make the field exported,ie you may declare the struct as

    type MyStruct struct {
        Field MyEnum
    }
    

    Here is a sample program with exported and unexported fields

    Code

    package main
    
    import (
        "fmt"
    )
    
    type MyEnum int
    
    const (
        Foo MyEnum = 1
        Bar MyEnum = 2
    )
    
    func (e MyEnum) String() string {
        switch e {
        case Foo:
            return "Foo"
        case Bar:
            return "Bar"
        default:
            return fmt.Sprintf("%d", int(e))
        }
    }
    
    type MyStruct struct {
        Field1 MyEnum
        field2 MyEnum
    }
    
    func main() {
        info := &MyStruct{
            Field1: MyEnum(1),
            field2: MyEnum(2),
        }
        fmt.Printf("%v
    ", MyEnum(1))
        fmt.Printf("%v
    ", info)
        fmt.Printf("%+v
    ", info)
        fmt.Printf("%#v
    ", info)
    }
    

    Output

    Foo
    &{Foo 2}
    &{Field1:Foo field2:2}
    &main.MyStruct{Field1:1, field2:2}
    

    Here is play link : https://play.golang.org/p/7knxM4KbLh

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