# 接口

（1）如何检测一个值`v`是否实现了接口`Stringer`：

```go
if v, ok := v.(Stringer); ok {
    fmt.Printf("implements String(): %s\n", v.String())
}
```

（2）如何使用接口实现一个类型分类函数：

```go
func classifier(items ...interface{}) {
    for i, x := range items {
        switch x.(type) {
        case bool:
            fmt.Printf("param #%d is a bool\n", i)
        case float64:
            fmt.Printf("param #%d is a float64\n", i)
        case int, int64:
            fmt.Printf("param #%d is an int\n", i)
        case nil:
            fmt.Printf("param #%d is nil\n", i)
        case string:
            fmt.Printf("param #%d is a string\n", i)
        default:
            fmt.Printf("param #%d’s type is unknown\n", i)
        }
    }
}
```

## 链接

* [目录](https://github.com/yangchuansheng/the-way-to-go_ZH_CN/tree/f30ab7d8c58f85840a0afb548024b93642b518d5/eBook/directory.md)
* 上一节：[结构体](https://ryanyang.gitbook.io/the-way-to-go-zh-cn/di-si-bu-fen-shi-ji-ying-yong/18.0/18.4)
* 下一节：[函数](https://ryanyang.gitbook.io/the-way-to-go-zh-cn/di-si-bu-fen-shi-ji-ying-yong/18.0/18.6)