Error CS0563 (One of the parameters of a binary operator must be the containing type)

My source code (below) is generating Error CS0563 because both of the parameters in my CombinedJobs operator+ (see "//Step 5: ..." in source code) are listed as Job (as opposed to int, double, etc). How can I change this code to eliminate this error? This code is in response to the assignment listed below.

Assignment:

"Design a Job class for Harold’s Home Services. The class contains four data fields—Job description (for example, “wash windows”), time in hours to complete the Job (for example, 3.5), per-hour rate charged for the Job (for example, $25.00), and total fee for the Job (hourly rate times hours). Include properties to get and set each field except the total fee—that field will be read-only, and its value is calculated each time either the hourly fee or the number of hours is set. Overload the + operator so that two Jobs can be added. The sum of two Jobs is a new Job containing the descriptions of both original Jobs ( joined by “and”), the sum of the time in hours for the original Jobs, and the average of the hourly rate for the original Jobs. Write a Main()function that demonstrates all the methods work correctly. Save the file as DemoJobs.cs."

From: Microsoft® Visual C#® 2008, An Introduction to Object-Oriented Programming, 3e, Joyce Farrell

Source Code:

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
         {
开发者_JAVA百科            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();

   }

}      

---

The operator+ method has to be inside the class of one of its parameters. Since in your case both parameters are Job, the method has to be inside the Job class. It can't be inside CombinedJobs.

Also, you declared the operator as returning CombinedJobs, so that means you have to actually return it. This is not causing the error you are describing, but it would cause another compile error.