Ôñüðïò ÷ñÞóçò ôùí äéáóõíäÝóåùí IComparable êáé IComparer óôï Visual C#

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IComparable

// Implement IComparable CompareTo method - provide default sort order.
int IComparable.CompareTo(object obj)
{
   car c=(car)obj;
   return String.Compare(this.make,c.make);

}
				

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IComparer

private class sortYearAscendingHelper : IComparer
{
   int IComparer.Compare(object a, object b)
   {
      car c1=(car)a;
      car c2=(car)b;
      if (c1.year > c2.year)
         return 1;
      if (c1.year < c2.year)
         return -1;
      else
         return 0;
   }
}
				

public static IComparer sortYearAscending()
{      
   return (IComparer) new sortYearAscendingHelper();
}
				

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ÐáñÜäåéãìá âÞìá ðñïò âÞìá

1. Óôç Visual C#, äçìéïõñãÞóôå Ýíá íÝï Ýñãï åöáñìïãÞò êïíóüëáò. Ôï üíïìá ôçò åöáñìïãÞò ConsoleEnum.
2. Ìåôïíïìáóßá Program.cs ùò Host.cs êáé óôç óõíÝ÷åéá íá áíôéêáôáóôÞóåôå ôïí êùäéêü ìå ôïí ðáñáêÜôù êþäéêá.
   
   Óçìåßùóç Óôï Visual Studio.NET 2003, ìåôïíïìÜóôå ôï Class1.cs ùò Host.cs.

   using System;
   
   namespace ConsoleEnum
   {
      class host
      {
         [STAThread]
         static void Main(string[] args)
         {
            // Create an arary of car objects.      
            car[] arrayOfCars= new car[6]
            {
               new car("Ford",1992),
               new car("Fiat",1988),
               new car("Buick",1932),
               new car("Ford",1932),
               new car("Dodge",1999),
               new car("Honda",1977)
            };
         
            // Write out a header for the output.
            Console.WriteLine("Array - Unsorted\n");
   
            foreach(car c in arrayOfCars)
               Console.WriteLine(c.Make + "\t\t" + c.Year);
         
            // Demo IComparable by sorting array with "default" sort order.
            Array.Sort(arrayOfCars);
            Console.WriteLine("\nArray - Sorted by Make (Ascending - IComparable)\n");
   
            foreach(car c in arrayOfCars)
               Console.WriteLine(c.Make + "\t\t" + c.Year);
   
            // Demo ascending sort of numeric value with IComparer.
            Array.Sort(arrayOfCars,car.sortYearAscending());
            Console.WriteLine("\nArray - Sorted by Year (Ascending - IComparer)\n");
   
            foreach(car c in arrayOfCars)
               Console.WriteLine(c.Make + "\t\t" + c.Year);
   
            // Demo descending sort of string value with IComparer.
            Array.Sort(arrayOfCars,car.sortMakeDescending());
            Console.WriteLine("\nArray - Sorted by Make (Descending - IComparer)\n");
   
            foreach(car c in arrayOfCars)
               Console.WriteLine(c.Make + "\t\t" + c.Year);
   
            // Demo descending sort of numeric value using IComparer.
            Array.Sort(arrayOfCars,car.sortYearDescending());
            Console.WriteLine("\nArray - Sorted by Year (Descending - IComparer)\n");
   
            foreach(car c in arrayOfCars)
               Console.WriteLine(c.Make + "\t\t" + c.Year);
        
            Console.ReadLine();
         }
      }
   }
   					

3. ÐñïóèÞêç ìéáò êëÜóçò óôï Ýñãï. Ôï üíïìá ôçò êëÜóçò áõôïêßíçôï.
4. ÁíôéêáôÜóôáóç êþäéêá Car.cs ìå ôï åîÞò:

   using System;
   using System.Collections;
   namespace ConsoleEnum
   {   
      public class car : IComparable
      {      
         // Beginning of nested classes.
   
         // Nested class to do ascending sort on year property.
         private class sortYearAscendingHelper: IComparer
         {
            int IComparer.Compare(object a, object b)
            {
               car c1=(car)a;
               car c2=(car)b;
   
               if (c1.year > c2.year)
                  return 1;
   
               if (c1.year < c2.year)
                  return -1;
   
               else
                  return 0;
            }
         }
   
         // Nested class to do descending sort on year property.
         private class sortYearDescendingHelper: IComparer
         {
            int IComparer.Compare(object a, object b)
            {
               car c1=(car)a;
               car c2=(car)b;
   
               if (c1.year < c2.year)
                  return 1;
   
               if (c1.year > c2.year)
                  return -1;
   
               else
                  return 0;
            }
         }
   
         // Nested class to do descending sort on make property.
         private class sortMakeDescendingHelper: IComparer
         {
            int IComparer.Compare(object a, object b)
            {
               car c1=(car)a;
               car c2=(car)b;
                return String.Compare(c2.make,c1.make);
            }
         }
   
         // End of nested classes.
   
         private int year;
         private string make;
           
         public car(string Make,int Year)
         {
            make=Make;
            year=Year;
         }
   
         public int Year
         {
            get  {return year;}
            set {year=value;}
         }
   
         public string Make
         {
            get {return make;}
            set {make=value;}
         }
   
         // Implement IComparable CompareTo to provide default sort order.
         int IComparable.CompareTo(object obj)
         {
            car c=(car)obj;
            return String.Compare(this.make,c.make);
         }
   
         // Method to return IComparer object for sort helper.
         public static IComparer sortYearAscending()
         {      
            return (IComparer) new sortYearAscendingHelper();
         }
   
         // Method to return IComparer object for sort helper.
         public static IComparer sortYearDescending()
         {      
            return (IComparer) new sortYearDescendingHelper();
         }
   
         // Method to return IComparer object for sort helper.
         public static IComparer sortMakeDescending()
         {      
           return (IComparer) new sortMakeDescendingHelper();
         }
   
      }
   }
   					

5. ÅêôÝëåóç ôïõ Ýñãïõ. Óôï ðáñÜèõñï êïíóüëáò åìöáíßæåôáé ôï áêüëïõèï áðïôÝëåóìá:

   Array - Unsorted
   
   Ford            1992
   Fiat            1988
   Buick           1932
   Ford            1932
   Dodge           1999
   Honda           1977
   
   Array - Sorted by Make (Ascending - IComparable)
   
   Buick           1932
   Dodge           1999
   Fiat            1988
   Ford            1932
   Ford            1992
   Honda           1977
   
   Array - Sorted by Year (Ascending - IComparer)
   
   Ford            1932
   Buick           1932
   Honda           1977
   Fiat            1988
   Ford            1992
   Dodge           1999
   
   Array - Sorted by Make (Descending - IComparer)
   
   Honda           1977
   Ford            1932
   Ford            1992
   Fiat            1988
   Dodge           1999
   Buick           1932
   
   Array - Sorted by Year (Descending - IComparer)
   
   Dodge           1999
   Ford            1992
   Fiat            1988
   Honda           1977
   Buick           1932
   Ford            1932
   					

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