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。

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任务：

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“为 Harold\xe2\x80\x99s Home Services 设计一个 Job 类。该类包含四个数据字段\xe2\x80\x94Job\n描述（例如，\xe2\x80\x9cwash windows\xe2\x80\x9d）、时间完成作业的小时数（例如，\n3.5）、作业的每小时费率（例如，25.00 美元）以及作业的总费用\n（每小时费率乘以小时数）。包括获取和设置每个作业的属性字段，\n总费用\xe2\x80\x94 除外，该字段为只读，并且每次\n设置每小时费用或\n小时数时都会计算其值。重载 + 运算符，以便可以\n创建两个作业添加。两个作业的总和是一个新作业，其中包含两个\原始作业的描述（由 \xe2\x80\x9cand\xe2\x80\x9d 连接）、原始作业的时间总和（以小时为单位），以及\ “原始作业的每小时平均费率。编写一个 Main() 函数，\n演示所有方法都能正常工作。将文件另存为 DemoJobs.cs。”

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来自：Microsoft\xc2\xae Visual C#\xc2\xae 2008，面向对象编程简介，3e，Joyce Farrell

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源代码：

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using System;\n\n//Step 1: Creating the Job class and designating its fields\n\n   public class Job\n\n   {\n\n      private string jobDescription;\n\n      private int jobTotalTime;\n\n      private double jobRate;\n\n      private double jobTotalFee;\n\n\n//Step 2: Using the \'this\' object will allow me to designate values for \n\n//"this" instantiation of an object later in the program\n\n      public string JobDescription\n      {\n         get\n         {\n            return this.jobDescription;\n         }\n         set\n         {\n            this.jobDescription = value;\n         }\n      }  \n\n      public int JobTotalTime\n      {\n         get\n         {\n            return this.jobTotalTime;\n         }\n         set\n         {\n            this.jobTotalTime = value;\n         }\n      }  \n\n     public double JobRate\n      {\n         get\n         {\n            return this.jobRate;\n         }\n         set\n         {\n            this.jobRate = value;\n         }\n      }       \n\n    public double JobTotalFee\n      {\n         get\n         {\n            return this.jobTotalFee;\n         }\n         set\n         {\n            this.jobTotalFee = this.JobRate * this.JobTotalTime;\n         }\n      }  \n\n//Step 3: Creating a method will allow me to display the different jobs \n\n//with their descriptions and other variable fields later in the program\n\n   public void JobMessage()\n\n   {\n\n      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);\n\n   }\n\n\n}\n\n//Step 4: Creating two instantiations of the Job Class\n\npublic class CreateTwoJobs\n\n{\n\n   public static void Main()\n\n   {\n\n   Job jobA = new Job();\n\n   Job jobB = new Job();\n\n\n   jobA.JobDescription = "washing windows";\n\n   jobA.JobTotalTime = 5;\n\n   jobA.JobRate = 25.00;\n\n\n   jobB.JobDescription = "walking dogs";\n\n   jobB.JobTotalTime = 10;\n\n   jobB.JobRate = 11.00;\n\n\n   jobA.JobMessage();\n\n   jobB.JobMessage();\n\n   }\n\n}\n\n\n//Step 5: Creating a third instantiation of the Job Class that is a combination \n\n//of the first two instantiations using the overloaded + operator\n\n\npublic class CombinedJobs\n\n{\n\n   public CombinedJobs(string jobDescription, int jobTotalTime, double jobRate, double jobTotalFee)\n\n   {\n\n   JobDescription = jobDescription;\n\n   JobTotalTime = jobTotalTime;\n\n   JobRate = jobRate;\n\n   JobTotalFee = jobTotalFee;\n\n   }\n\n\n   public static CombinedJobs operator+(Job jobA, Job jobB)\n\n   {\n\n   string newDescription = jobA.JobDescription + " and " + jobB.JobDescription;\n\n   int newTotalTime = jobA.JobTotalTime + jobB.JobTotalTime;\n\n   double newJobRate = (jobA.JobRate + jobB.JobRate) / 2;\n\n   double newTotalFee = newJobRate * newTotalTime\n\n   }\n\n\n   public void CombinedJobMessage()\n\n   {\n\n      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);\n\n   }   \n\n\n   public static void Main()\n\n   {\n\n      CombinedJobMessage();\n\n   }\n\n}      \n

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Answer 1

该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类内部。它不可能在里面CombinedJobs。

另外，您将运算符声明为 returned CombinedJobs，因此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。