Question

1) Introduction to Objects (with Constructors and Properties)

We need to answer the question which are below.
and instruction are given down starting with part(b).

Just we need to copy paste code file and follow the instruction and answer related to them.

a) Enter the following program.Answer The questions below the codes, Notice that it consists of two classes that will go into the same project. Please put each class into its own code file (use Lab5_1 for the Project name and Lab5_1_1 / Lab5_1_2 for the Code File names). This program focuses on classes, objects and properties. Class EmployeeDemo is a static class that contains Main().

//Lab5_1_1

//code file

using System;
public static class EmployeeDemo
{
    public static void Main()
    {
        // Create Employee objects utilizing different constructors
        Employee emp1 = new Employee();
        // Employee emp2 = new Employee("Joy Rogers", 10127, "HR", "Manager");
        // Employee emp3 = new Employee("Mark Jones", 10065);

        // Use Properties to assign values to data fields
        // emp1.Name = "Susan Meyers";
        // emp1.IdNumber = 10012;
        // emp1.Department = "Accounting";
        // emp1.Position = "Vice President";

        // emp3.Department = "IT";
        // emp3.Position = "Support";

        // Use Properties to output data from Employee objects
        Console.WriteLine("Employee 1: {0}, {1}, {2}, {3}",
           emp1.Name, emp1.IdNumber, emp1.Department, emp1.Position);
        // Console.WriteLine("Employee 2: {0}, {1}, {2}, {3}", 
        //     emp2.Name, emp2.IdNumber, emp2.Department, emp2.Position);
        // Console.WriteLine("Employee 3: {0}, {1}, {2}, {3}", 
        //     emp3.Name, emp3.IdNumber, emp3.Department, emp3.Position);
        Console.ReadLine();
    }
}

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Lab5_1_2

// Code File

using System;   // Code File Lab5_1_2.cs
public class Employee   // this is a dynamic class (no “static”)
{
   private int idNumber;
   private string name, department, position;

   public Employee() // Constructor 1: No Arg
   {
      Name = "";
      IdNumber = 0;
      Department = "";
      Position = "";
   }
 
   public Employee(string eName, int eIdNum) // Constructor 2: Two Arg
   {
      Name = eName;
      IdNumber = eIdNum;
      Department = "";
      Position = "";
   }
 
   // Constructor 3: Four Arg
   public Employee(string eName, int eIdNum, string eDept, string ePos)
   {
      Name = eName;
      IdNumber = eIdNum;
      Department = eDept;
      Position = ePos;
   }
 
   public string Name   // Property for priviate data - name
   {
      get { return name; }
      set { name = value; }
   }
 
   public int IdNumber  // Property for priviate data - idNumber
   {
      get { return idNumber; }
      set { idNumber = value; }
   }
 
   public string Department     // Property for priviate data – department
   {
      get { return department; }
      set { department = value; }
   }

  public string Position        // Property for priviate data - position

  {
     get { return position; }
     set { position = value; }
  }
}

PDF Questions

b) Build and execute the program (F5) … resolve any syntax mistakes (if you make any) until the program compiles. What is the output? Which constructor from the Employee class was invoked to instantiate emp1 object? Why are the contents of the emp1 object appear to be empty when printed?

c) Uncomment Lines 12-15 in the EmployeeDemo class to render them active (i.e, remove the // from in front of the C# commands). Compile and execute the program (F5). What is the output? Why is the output for Employee 1 different that in Part (b)?

d) Uncomment Lines 8, 23, 24 in the EmployeeDemo class to render them active, execute the program (F5). What is the output? Which constructor from the Employee class was invoked to instantiate emp2 object?

e) Uncomment Lines 9, 25 and 26 in the EmployeeDemo class to render them active, execute the program (F5). What is the output? Which constructor from the Employee class was invoked to instantiate emp3 object?

f) Uncomment Lines 17 and 18 in the EmployeeDemo class to render them active, execute the program (F5). What is the output? Why is the output for Employee 3 different that in Part (e)?

g) In Line 13, change IdNumber to idNumber in the EmployeeDemo class (basically you are substituting a public property for a private name).

Run the program (F5). What happens and why?

n) In Line 4 of the Employee class (note the different file here), change private to public. Run the program (F5). What happens and why? Is it a good idea to solve the problem this way? Why?

Answer 1

b) Here is the output:

The default constructor (first one) is called as there is no parameter passed.

public Employee()
{ Name = "";
IdNumber = 0;
Department = "";
Position = "";
}

The object appeared to be empty when printed because we did not set the values of object properties.

c) Here is the output:

The output is different from the b) as now we assigned values to the object properties using below code.

emp1.Name = "Susan Meyers";
emp1.IdNumber = 10012;
emp1.Department = "Accounting";
emp1.Position = "Vice President";

d) Here is the output:

The third parameterized constructor was invoked to instantiate emp2 object as 4 parameter are passed.

public Employee(string eName, int eINum, strng eDept, string ePs)
{
Name = eName;
IdNmber = eIdNum;
Department = eDept
Position = ePos;
}

e) Here is the output:

The second parameterized constructor was invoked to instantiate emp3 object as 2 parameter are passed.

public Employee(string eName, int eIdNum)
{
Name = eName;
IdNumber = eIdNum;
Department = "";
Position = "";
}

f) Here is the output:

The output is different from the e) as now we assigned values to the object emp2 remaining properties using below code which were not set in the constructor.

emp3.Department = "IT";
emp3.Position = "Support";

g) It throws a compile-time error as idNumber is inaccessible due to its protection level. Private properties are only accessible within the class.

h) Changing line 4 to public removes the error that we were getting in g). This is because public members are accessible outside the class. This not a good idea to solve the problem as private members created for internal working only and allowing access to them will create problems in the program