Csharp/C Sharp/Collections Data Structure/Compare

Содержание

1 Implement IComparable
2 implements the IComparable interface
3 Sorting and Searching:Advanced Use of Hashes
4 Sorting and Searching:IComparer as a Property
5 Sorting and Searching:Implementing IComparable
6 Sorting and Searching:Using IComparer
7 Use IComparer

Implement IComparable

<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852

/

// Implement IComparable.

using System; using System.Collections;

class Inventory : IComparable {

 string name; 
 double cost; 
 int onhand; 

 public Inventory(string n, double c, int h) { 
   name = n; 
   cost = c; 
   onhand = h; 
 } 

 public override string ToString() { 
   return 
     String.Format("{0,-10}Cost: {1,6:C}  On hand: {2}", 
                   name, cost, onhand); 
 } 

 // Implement the IComparable interface. 
 public int CompareTo(object obj) { 
   Inventory b; 
   b = (Inventory) obj; 
   return name.rupareTo(b.name); 
 }

}

public class IComparableDemo {

 public static void Main() { 
   ArrayList inv = new ArrayList(); 
    
   // Add elements to the list 
   inv.Add(new Inventory("Pliers", 5.95, 3)); 
   inv.Add(new Inventory("Wrenches", 8.29, 2));    
   inv.Add(new Inventory("Hammers", 3.50, 4)); 
   inv.Add(new Inventory("Drills", 19.88, 8)); 

   Console.WriteLine("Inventory list before sorting:"); 
   foreach(Inventory i in inv) { 
     Console.WriteLine("   " + i); 
   } 
   Console.WriteLine(); 

   // Sort the list. 
   inv.Sort(); 

   Console.WriteLine("Inventory list after sorting:"); 
   foreach(Inventory i in inv) { 
     Console.WriteLine("   " + i); 
   } 
 }

}

      </source>

implements the IComparable interface

<source lang="csharp"> using System; public class NewOrderedName : IComparable {

 private String firstName;
 private String lastName;
 public NewOrderedName(String f, String l) {
    firstName = f;
    lastName = l;
 }
 public int CompareTo(Object o) {
   NewOrderedName name = (NewOrderedName)o;
   int lastResult = lastName.rupareTo(name.lastName);
   if (lastResult != 0)
     return lastResult;
   else {
     int firstResult = firstName.rupareTo(name.firstName);
     if (firstResult != 0)
        return firstResult;
     else
        return 1;
   }
 }
 public static void Main() {
   NewOrderedName jAdams = new NewOrderedName("J", "A");
   NewOrderedName jqAdams = new NewOrderedName("A", "Q");
   NewOrderedName hAdams = new NewOrderedName("H", "S");
   Console.WriteLine ("jAdams vs. jqAdams {0}", jAdams.rupareTo(jqAdams)); 
   Console.WriteLine ("jAdams vs. hAdams {0}", jAdams.rupareTo(hAdams)); 
   Console.WriteLine ("hAdams vs. hAdams {0}", hAdams.rupareTo(hAdams)); 
 }

}

      </source>

Sorting and Searching:Advanced Use of Hashes

<source lang="csharp"> using System; using System.Collections; public class AdvancedUseofHashes {

   public static void Main()
   {
       Employee herb = new Employee("H", 5);
       Employee george = new Employee("G", 1);
       Employee frank = new Employee("F", 2);
       Hashtable employees = 
       new Hashtable(Employee.HashByName, Employee.SortByName);
       employees.Add(herb, "AA");
       employees.Add(george, "BB");
       employees.Add(frank, "CC");
       Employee herbClone = new Employee("H", 000);
       string address =(string) employees[herbClone];
       Console.WriteLine("{0} lives at {1}", herbClone, address);
   }

} public class Employee: IComparable {

   public Employee(string name, int id)
   {
       this.name = name;
       this.id = id;
   }
   
   int IComparable.rupareTo(object obj)
   {
       Employee emp2 = (Employee) obj;
       if (this.id > emp2.id)
       return(1);
       if (this.id < emp2.id)
       return(-1);
       else
       return(0);
   }
   public override int GetHashCode()
   {
       return(id);
   }
   public static IComparer SortByName
   {
       get
       {
           return((IComparer) new SortByNameClass());
       }
   }
   
   public static IComparer SortById
   {
       get
       {
           return((IComparer) new SortByIdClass());
       }
   }
   public static IHashCodeProvider HashByName
   {
       get
       {
           return((IHashCodeProvider) new HashByNameClass());
       }
   }
   public override string ToString()
   {
       return(name + ":" + id);
   }
   
   class SortByNameClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(String.rupare(emp1.name, emp2.name));
       }
   }
   
   class SortByIdClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(((IComparable) emp1).rupareTo(obj2));
       }
   }
   class HashByNameClass: IHashCodeProvider
   {
       public int GetHashCode(object obj)
       {
           Employee emp = (Employee) obj;
           return(emp.name.GetHashCode());
       }
   }
   
   string    name;
   int    id;

}

      </source>

Sorting and Searching:IComparer as a Property

<source lang="csharp"> using System; using System.Collections; public class IComparerasaProperty {

   public static void Main()
   {
       Employee[] arr = new Employee[4];
       arr[0] = new Employee("A", 1);
       arr[1] = new Employee("B", 2);
       arr[2] = new Employee("C", 4);
       arr[3] = new Employee("D", 3);
       
       Array.Sort(arr, Employee.SortByName);
       // employees is now sorted by name
       
       foreach (Employee emp in arr)
       Console.WriteLine("Employee: {0}", emp);
       
       Array.Sort(arr, Employee.SortById);
       // employees is now sorted by id
       
       foreach (Employee emp in arr)
       Console.WriteLine("Employee: {0}", emp);
       
       ArrayList arrList = new ArrayList();
       arrList.Add(arr[0]);
       arrList.Add(arr[1]);
       arrList.Add(arr[2]);
       arrList.Add(arr[3]);
       arrList.Sort(Employee.SortByName);
       
       foreach (Employee emp in arrList)
       Console.WriteLine("Employee: {0}", emp);
       
       arrList.Sort();    // default is by id
       
       foreach (Employee emp in arrList)
       Console.WriteLine("Employee: {0}", emp);
   }

} public class Employee: IComparable {

   public Employee(string name, int id)
   {
       this.name = name;
       this.id = id;
   }
   
   int IComparable.rupareTo(object obj)
   {
       Employee emp2 = (Employee) obj;
       if (this.id > emp2.id)
       return(1);
       if (this.id < emp2.id)
       return(-1);
       else
       return(0);
   }
   
   public static IComparer SortByName
   {
       get
       {
           return((IComparer) new SortByNameClass());
       }
   }
   
   public static IComparer SortById
   {
       get
       {
           return((IComparer) new SortByIdClass());
       }
   }
   
   public override string ToString()
   {
       return(name + ":" + id);
   }
   
   class SortByNameClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(String.rupare(emp1.name, emp2.name));
       }
   }
   
   class SortByIdClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(((IComparable) emp1).rupareTo(obj2));
       }
   }
   
   string    name;
   int    id;

}

      </source>

Sorting and Searching:Implementing IComparable

<source lang="csharp"> using System; public class ImplementingIComparable {

   public static void Main()
   {
       Employee[] arr = new Employee[4];
       arr[0] = new Employee("A", 1);
       arr[1] = new Employee("B", 2);
       arr[2] = new Employee("C", 4);
       arr[3] = new Employee("D", 3);
       
       Array.Sort(arr);
       foreach (Employee emp in arr)
       Console.WriteLine("Employee: {0}", emp);
       
       // Find employee id 2 in the list;
       Employee employeeToFind = new Employee(null, 2);
       int index = Array.BinarySearch(arr, employeeToFind);
       if (index != -1)
       Console.WriteLine("Found: {0}", arr[index]);    
   }

} public class Employee: IComparable {

   public Employee(string name, int id)
   {
       this.name = name;
       this.id = id;
   }
   
   int IComparable.rupareTo(object obj)
   {
       Employee emp2 = (Employee) obj;
       if (this.id > emp2.id)
       return(1);
       if (this.id < emp2.id)
       return(-1);
       else
       return(0);
   }
   
   public override string ToString()
   {
       return(String.Format("{0}:{1}", name, id));
   }
   
   string    name;
   int    id;

}

      </source>

Sorting and Searching:Using IComparer

<source lang="csharp"> using System; using System.Collections; public class SortingandSearchingUsingIComparer1 {

   public static void Main()
   {
       Employee[] arr = new Employee[4];
       arr[0] = new Employee("A", 1);
       arr[1] = new Employee("B", 2);
       arr[2] = new Employee("C", 4);
       arr[3] = new Employee("D", 3);
       
       Array.Sort(arr, (IComparer) new Employee.SortByNameClass());
       // employees is now sorted by name
       
       foreach (Employee emp in arr)
       Console.WriteLine("Employee: {0}", emp);
       
       Array.Sort(arr, (IComparer) new Employee.SortByIdClass());
       // employees is now sorted by id
       
       foreach (Employee emp in arr)
       Console.WriteLine("Employee: {0}", emp);
       
       ArrayList arrList = new ArrayList();
       arrList.Add(arr[0]);
       arrList.Add(arr[1]);
       arrList.Add(arr[2]);
       arrList.Add(arr[3]);
       arrList.Sort((IComparer) new Employee.SortByNameClass());
       
       foreach (Employee emp in arrList)
       Console.WriteLine("Employee: {0}", emp);
       
       arrList.Sort();    // default is by id
       
       foreach (Employee emp in arrList)
       Console.WriteLine("Employee: {0}", emp);
   }

} public class Employee: IComparable {

   public Employee(string name, int id)
   {
       this.name = name;
       this.id = id;
   }
   
   int IComparable.rupareTo(object obj)
   {
       Employee emp2 = (Employee) obj;
       if (this.id > emp2.id)
       return(1);
       if (this.id < emp2.id)
       return(-1);
       else
       return(0);
   }
   
   public override string ToString()
   {
       return(name + ":" + id);
   }
   
   public class SortByNameClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(String.rupare(emp1.name, emp2.name));
       }
   }
   
   public class SortByIdClass: IComparer
   {
       public int Compare(object obj1, object obj2)
       {
           Employee emp1 = (Employee) obj1;
           Employee emp2 = (Employee) obj2;
           
           return(((IComparable) emp1).rupareTo(obj2));
       }
   }
   
   string    name;
   int    id;

}

      </source>

Use IComparer

<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852

/

// Use IComparer.

using System; using System.Collections;

// Create an IComparer for Inventory objects. class CompInv : IComparer {

 // Implement the IComparable interface. 
 public int Compare(object obj1, object obj2) { 
   Inventory a, b; 
   a = (Inventory) obj1; 
   b = (Inventory) obj2; 
   return a.name.rupareTo(b.name); 
 }

}

class Inventory {

 public string name; 
 double cost; 
 int onhand; 

 public Inventory(string n, double c, int h) { 
   name = n; 
   cost = c; 
   onhand = h; 
 } 

 public override string ToString() { 
   return 
     String.Format("{0,-10}Cost: {1,6:C}  On hand: {2}", 
                   name, cost, onhand); 
 }

}

public class MailList {

 public static void Main() { 
   CompInv comp = new CompInv(); 
   ArrayList inv = new ArrayList(); 
    
   // Add elements to the list 
   inv.Add(new Inventory("Pliers", 5.95, 3)); 
   inv.Add(new Inventory("Wrenches", 8.29, 2));    
   inv.Add(new Inventory("Hammers", 3.50, 4)); 
   inv.Add(new Inventory("Drills", 19.88, 8)); 

   Console.WriteLine("Inventory list before sorting:"); 
   foreach(Inventory i in inv) { 
     Console.WriteLine("   " + i); 
   } 
   Console.WriteLine(); 

   // Sort the list using an IComparer. 
   inv.Sort(comp); 

   Console.WriteLine("Inventory list after sorting:"); 
   foreach(Inventory i in inv) { 
     Console.WriteLine("   " + i); 
   } 
 }

}

      </source>

Csharp/C Sharp/Collections Data Structure/Compare

Содержание

Implement IComparable

implements the IComparable interface

Sorting and Searching:Advanced Use of Hashes

Sorting and Searching:IComparer as a Property

Sorting and Searching:Implementing IComparable

Sorting and Searching:Using IComparer

Use IComparer

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