错误CS0563（二元运算符的参数之一必须是包含类型）

Question

我的源代码（如下）正在生成错误 CS0563，因为我的 CombinedJobs 运算符+（请参阅源代码中的“//Step 5：...”）中的两个参数都被列为 Job（而不是 int、double 等）。我该如何更改此代码以消除此错误？此代码是为了响应下面列出的分配。

作业：

“为 Harold 的家庭服务设计一个 Job 类。该类包含四个数据字段 — Job 描述（例如“清洗窗户”）、完成作业的时间（例如 例如，3.5）、该工作的每小时费率（例如，25.00 美元）以及总费用 工作（每小时费率乘以小时数）。包括用于获取和设置每个字段的属性，除了 总费用 - 该字段将是只读的，并且每次都会计算其值 设定每小时费用或小时数。重载 + 运算符，以便两个作业 可以添加。两个作业的总和是一个新作业，包含两个作业的描述 原始作业（由“和”连接），原始作业的时间总和（以小时为单位），以及 原始职位的平均每小时工资。编写一个 Main() 函数 证明所有方法都能正常工作。将文件另存为 DemoJobs.cs。”

来自：Microsoft® Visual C#® 2008，面向对象编程简介，3e，Joyce Farrell

源代码：

using System;

//Step 1: Creating the Job class and designating its fields

   public class Job

   {

      private string jobDescription;

      private int jobTotalTime;

      private double jobRate;

      private double jobTotalFee;


//Step 2: Using the 'this' object will allow me to designate values for 

//"this" instantiation of an object later in the program

      public string JobDescription
      {
         get
         {
            return this.jobDescription;
         }
         set
         {
            this.jobDescription = value;
         }
      }  

      public int JobTotalTime
      {
         get
         {
            return this.jobTotalTime;
         }
         set
         {
            this.jobTotalTime = value;
         }
      }  

     public double JobRate
      {
         get
         {
            return this.jobRate;
         }
         set
         {
            this.jobRate = value;
         }
      }       

    public double JobTotalFee
      {
         get
         {
            return this.jobTotalFee;
         }
         set
         {
            this.jobTotalFee = this.JobRate * this.JobTotalTime;
         }
      }  

//Step 3: Creating a method will allow me to display the different jobs 

//with their descriptions and other variable fields later in the program

   public void JobMessage()

   {

      Console.WriteLine("Job description: {0} /nTotal time needed to complete the job: {1} hours /nHourly fee: ${2} /nTotal fee for the job is: ${3}", this.JobDescription, this.JobTotalTime, this.JobRate, this.JobTotalFee);

   }


}

//Step 4: Creating two instantiations of the Job Class

public class CreateTwoJobs

{

   public static void Main()

   {

   Job jobA = new Job();

   Job jobB = new Job();


   jobA.JobDescription = "washing windows";

   jobA.JobTotalTime = 5;

   jobA.JobRate = 25.00;


   jobB.JobDescription = "walking dogs";

   jobB.JobTotalTime = 10;

   jobB.JobRate = 11.00;


   jobA.JobMessage();

   jobB.JobMessage();

   }

}


//Step 5: Creating a third instantiation of the Job Class that is a combination 

//of the first two instantiations using the overloaded + operator


public class CombinedJobs

{

   public CombinedJobs(string jobDescription, int jobTotalTime, double jobRate, double jobTotalFee)

   {

   JobDescription = jobDescription;

   JobTotalTime = jobTotalTime;

   JobRate = jobRate;

   JobTotalFee = jobTotalFee;

   }


   public static CombinedJobs operator+(Job jobA, Job jobB)

   {

   string newDescription = jobA.JobDescription + " and " + jobB.JobDescription;

   int newTotalTime = jobA.JobTotalTime + jobB.JobTotalTime;

   double newJobRate = (jobA.JobRate + jobB.JobRate) / 2;

   double newTotalFee = newJobRate * newTotalTime

   }


   public void CombinedJobMessage()

   {

      Console.WriteLine("Job description: {0} /nTotal time needed to complete the job: {1} hours /nHourly fee: ${2} /nTotal fee for the job is: ${3}", newDescription, newTotalTime, newJobRate, newTotalTime);

   }   


   public static void Main()

   {

      CombinedJobMessage();

   }

}      

Answer 1

operator+ 方法必须位于其参数之一的类内部。由于在您的情况下，两个参数都是 Job，因此该方法必须位于 Job 类内。它不能位于 CombinedJobs 内部。

另外，您将运算符声明为返回CombinedJobs，这意味着您必须实际返回它。这不会导致您所描述的错误，但会导致另一个编译错误。