GO语言面试系列:(九)golang强制类型转换示例(usafe包)

题目:

设计父结构体—员工。子结构体:工人,农民,教师,科学家(scientist),服务生。
(1)其中工人,农民,服务生只有基本工资。(10分)
(2)教师除基本工资外,还有课酬(元/天)。(10分)
(3)科学家除基本工资外,还有年终奖。(10分)
编写一个测试结构体,将各种类型的员工的全年工资打印出来。(10分)

代码示例:

package main
import (
 "fmt"
 "unsafe"
)
type Employee struct {
 //基本工资
 BaseWage float64
 eType E_TYPE //员工类型
}
type E_TYPE string
const (
 WORKER E_TYPE = "工人"
 FARMER = "农民"
 TEACHER2 = "老师"
 SCIENTIST = "科学家"
 WAITER = "服务员"
)
type Worker struct {
 Employee
}
func (e *Employee) getYearBaseSalary() float64 {
 return 12 * e.BaseWage
}
func (e *Employee) PrintSalary() {
 fmt.Printf("%s全年工资:", e.eType)
 switch e.eType {
 case WORKER:
 fallthrough
 case FARMER:
 fallthrough
 case WAITER:
 fmt.Printf("%.2f\n", e.BaseWage)
 case TEACHER2:
 //下面使用unsafe包的Pointer将父类(Employee)实例转为子类(Teacher2)实例
 //将父类实例转为通用指针
 uP := unsafe.Pointer(e)
 //再转换为本地 Teacher2 结构体
 pT := (*Teacher2)(uP)
 //转换完毕,可以输出子类特有属性
 fmt.Println("测试-->老师的课酬是:", pT.ClassRemuneration)
 fmt.Printf("%.2f\n", e.getYearBaseSalary()+pT.ClassRemuneration)
 case SCIENTIST:
 uP := unsafe.Pointer(e)
 pT := (*Scientist)(uP)
 fmt.Printf("%.2f\n", e.getYearBaseSalary()+pT.YearEndBonus)
 default:
 fmt.Println("未能匹配到对应的员工类型")
 }
}
type Farmer struct {
 Employee
}
type Teacher2 struct {
 Employee
 //课酬 (元/天)
 ClassRemuneration float64
}
type Scientist struct {
 Employee
 //年终奖
 YearEndBonus float64
}
type Waiter struct {
 Employee
}
//----------------测试------------------------
func main() {
 //实例化工人
 var worker *Worker = &Worker{Employee: Employee{BaseWage: 120, eType: WORKER}}
 //实例化农民
 var farmer *Farmer = &Farmer{
 Employee: Employee{
 BaseWage: 150,
 eType: FARMER,
 },
 }
 //实例化老师
 employee := &Employee{BaseWage: 250, eType: TEACHER2}
 var teacher2 *Teacher2 = &Teacher2{Employee: *employee}
 teacher2.ClassRemuneration = 500
 //实例化科学家
 var scientist *Scientist = &Scientist{
 Employee{BaseWage: 300, eType: SCIENTIST},
 200,
 }
 //实例化服务人员
 var waiter *Waiter = &Waiter{Employee: Employee{BaseWage: 150, eType: WAITER}}
 //测试输出
 worker.PrintSalary()
 farmer.PrintSalary()
 waiter.PrintSalary()
 teacher2.PrintSalary()
 scientist.PrintSalary()
}

运行结果:

从以上代码中可以看到,我们没有使用接口,给父类绑定一个方法PrintSalary,子类就都可以使用这个方法了,然后在该方法内对父类型强转成了子类型。

感谢作者:波涛澎湃
参考链接:https://www.jianshu.com/p/402c79820fa8?utm_campaign=studygolang.com&utm_medium=studygolang.com&utm_source=studygolang.com

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