IComparable

14y1.4kVisual Basic .NET

Program in the following website is altered (http://www.c-sharpcorner.com/UploadFile/prasadh/IComparablePSD12062005010125AM/IComparablePSD.aspx)

Whether it is < or > output is same. Please explain the reason. Problem is highlighted.

using System;
class Employee : IComparable
{
private int Id;

public Employee(int id)
{
this.Id = id;

}
public int CompareTo(object obj)
{
Employee temp = (Employee)obj;

if (this.Id < temp.Id) //if(this.Id>temp.Id)
return 1;
else
if (temp.Id == this.Id)
return 0;
else
return -1;

}
public static void Main()
{
Employee[] employees = new Employee[5];

Console.WriteLine("Before Sort:");
for (int i = 0; i < employees.Length; i++)
{
employees[i] = new Employee(5 - i);
Console.Write("{0}, ", 5-i);
}
Console.WriteLine("\n");

Array.Sort(employees);
Console.WriteLine("After Sort:");
for (int i = 0; i < employees.Length; i++)
{
Console.Write("{0}, ", 5 - i);
}
Console.WriteLine();
Console.ReadKey();
}
}

/*
Before Sort:
5, 4, 3, 2, 1,

After Sort:
5, 4, 3, 2, 1,
*/

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
If you change the name of the class from CreateEmployee to Employee then you have implemented it.

All the code is in the same class and so the static Main method can access the private instance field idNumber of the myAssistant object.
14y ago
Thank you very much for your help.
14y ago
How can this concept be implemented in this simple program.

using System;
public class CreateEmployee
{
public static void Main()
{
Employee myAssistant = new Employee(123);

Console.WriteLine("ID # is {0}", myAssistant.idNumber);

Console.ReadKey();
}

private int idNumber;

public Employee(int idNumber)
{
this.idNumber = idNumber;
}
}
Vulpes14y ago
Well, employees[i] returns an Employee instance - the i'th element of the array - and Id is its private instance field.

We're able to access this private field here because all the code, including the Main() method, is within the Employee class itself - we don't need to expose it via a public property.
14y ago
Thank you very much for your help.

I couldn't understand

Console.Write("{0}, ", employees[i].Id);

Because object.method is in get and set method or object.instanceVariable in automatic properties are familiar with. But here object.instanceVariable is coming again. Is there any additional explanation for that.
Vulpes14y ago
Just make the 3 highlighted changes:

using System;

class Employee : IComparable
{
private int Id;

public Employee(int id)
{
this.Id = id;

}
public int CompareTo(object obj)
{
Employee temp = (Employee)obj;

if (this.Id > temp.Id)
return 1;
else
if (temp.Id == this.Id)
return 0;
else
return -1;

}
public static void Main()
{
Employee[] employees = new Employee[5];

Console.WriteLine("Before Sort:");
for (int i = 0; i < employees.Length; i++)
{
employees[i] = new Employee(5 - i);
Console.Write("{0}, ", employees[i].Id);
}
Console.WriteLine("\n");

Array.Sort(employees);
Console.WriteLine("After Sort:");
for (int i = 0; i < employees.Length; i++)
{
Console.Write("{0}, ", employees[i].Id);
}
Console.WriteLine();
Console.ReadKey();
}
}

/*
Before Sort:
5, 4, 3, 2, 1,

After Sort:
1, 2, 3, 4, 5,
*/
14y ago
Is there any way to alter this program to get following output without the original program structure.

/*
Before Sort:
5, 4, 3, 2, 1,

After Sort:
1, 2, 3, 4, 5
*/
Vulpes14y ago
It's returning the same order whatever you do because it's not actually printing the elements of the array!

It's printing the numbers 5 to 1 in decreasing order using this line where i ranges from 0 to 4:

Console.Write("{0}, ", 5 - i);