c# - 并非所有代码路径都在方法中返回带有输出参数的值

Question

我正在练习构建一个虚拟应用程序，我正在尝试将枚举作为参数传入，并具有一个整数输出参数，该参数将用于设置成员变量 (BillsOwed) .我有两个具体问题:为什么 ComputeRetirementBenefitCost 告诉我必须在控制离开当前方法之前分配我的变量 以及为什么不是 ComputeRetirementBenefitCost 可访问我在评论中标记的位置？欢迎任何和所有审慎的 future 设计建议:)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace GivePromotions
{
    //Different Employees in the EmpType enum extend this class
    public abstract class Employee
    {
        public int EmployeeId { get; set; }
        public string LastName { get; set; }
        public string FirstName { get; set; }
        public DateTime DateHired { get; set; }
        public RetirementPackage.RetirementPackageType PackageType { get; set; }
        public EmpType Employeetype { get; set; }
        public int NetSalary { get; set; }

        //I'd like to set the output of ComputeRetirementBenefitCost
        //in the member below but Intellisense doesn't pick it up
        //on two lines for space, commented because it doesn't work  
        //int billsOwed = Employee.RetirementPackage
        //.ComputeRetirementBenefitCost(Employee.EmpType,out benefitCost)
        public virtual void DisplayInformation()
        {
            Console.WriteLine("Employee information: ");
            Console.WriteLine("EmployeeId = {0} ", EmployeeId);
            Console.WriteLine("Last name  = {0} ", LastName);
            Console.WriteLine("First name = {0} ", FirstName);
            Console.WriteLine("Date hired = {0} ", DateHired);
            Console.WriteLine("Salary     = {0} ", NetSalary);
        }

        public enum EmpType
        {
            Janitor,
            President,
            Manager
        }



        //an Employee 'has-a' Retirement package
        public class RetirementPackage
        {

            public enum RetirementPackageType
            {
                Basic,
                Gold,
                Silver,
                Platinum,
                Black
            }
        //method of choice here 
        //ERROR: Output parameter 'benefitCost' must be assigned to before control
        //leaves the current method
        public void ComputeRetirementBenefitCost(Employee.EmpType e, out int benefitCost)
        {   

                switch (e)
                {
                    case Employee.EmpType.President:
                         benefitCost = 100000;
                         break;
                    case Employee.EmpType.Manager:
                         benefitCost = 5000;
                         break;
                    case Employee.EmpType.Janitor:
                         benefitCost = 1000;
                         break; 



                }


            }

        }
    }


}

Answer 1

• 错误:必须在控制之前分配输出参数“benefitCost”:

您必须向您的开关添加一个“默认值:”或在您的开关之外设置一个值，因为这可能是您的三种情况都没有被命中。

• 为什么无法访问 ComputeRetirementBenefitCost

修复第一个将修复这个。使用crtl+shif+B构建并读取错误 ListView 中的错误和警告。通常他们会准确地告诉您哪里出了问题。