检查变量类型

在某些情况下，从函数返回变量时，你无法确定变量的类型。如果你不确定它是什么类型，你可以使用 var.(type) 检查变量的类型：

x := someFunction() // Some value of an unknown type is stored in x now

switch x := x.(type) {
    case bool:
        fmt.Printf("boolean %t\n", x)             // x has type bool
    case int:
        fmt.Printf("integer %d\n", x)             // x has type int
    case string:
        fmt.Printf("pointer to boolean %s\n", x) // x has type string
    default:
        fmt.Printf("unexpected type %T\n", x)     // %T prints whatever type x is
}