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==ComplexNumber: Implement System.IComparable==

<source lang="csharp">public class ComplexNumber : System.IComparable
{
public ComplexNumber( int real, int imaginary )
{
this.real = real;
this.imaginary = imaginary;
}
public override bool Equals( object obj )
{
ComplexNumber other = obj as ComplexNumber;
if( other == null )
{
return false;
}
return (this.real == other.real) && (this.imaginary == other.imaginary);
}
public override int GetHashCode()
{
return (int) real ^ (int) imaginary;
}
public static bool operator==( ComplexNumber me, ComplexNumber other )
{
return Equals( me, other );
}
public static bool operator!=( ComplexNumber me, ComplexNumber other )
{
return Equals( me, other );
}
public double Magnitude
{
get
{
return System.Math.Sqrt( System.Math.Pow(this.real, 2) + System.Math.Pow(this.imaginary, 2) );
}
}
public int CompareTo( object obj )
{
if( obj is ComplexNumber )
{
ComplexNumber other = (ComplexNumber) obj;
if( (this.real == other.real) &&
(this.imaginary == other.imaginary) )
{
return 0;
}
else if( this.Magnitude < other.Magnitude )
{
return -1;
}
else
{
return 1;
}
}
else
{
throw new System.ArgumentException( "Wrong type" );
}
}
private double real;
private double imaginary;
}
public class MainClass
{
static void Main()
{
ComplexNumber number1 = new ComplexNumber( 1, 2 );
ComplexNumber number2 = new ComplexNumber( 1, 2 );
ComplexNumber number3 = new ComplexNumber( 1, 3 );
System.Console.WriteLine( number1.rupareTo(number2) );
System.Console.WriteLine( number1.rupareTo(number3) );
}
}</source>
<pre class=codeResult>0
-1</pre>

==Define your own comparasion type and Comparer==

<source lang="csharp">using System;
using System.Collections.Generic;
public class Employee : IComparable<Employee>
{
private int empID;
private int yearsOfSvc = 1;
public Employee(int empID)
{
this.empID = empID;
}
public Employee(int empID, int yearsOfSvc)
{
this.empID = empID;
this.yearsOfSvc = yearsOfSvc;
}
public override string ToString()
{
return "ID: " + empID.ToString() + ". Years of Svc: " + yearsOfSvc.ToString();
}
public bool Equals(Employee other)
{
if (this.empID == other.empID)
{
return true;
}
else
{
return false;
}
}
public static EmployeeComparer GetComparer()
{
return new Employee.EmployeeComparer();
}
public int CompareTo(Employee rhs)
{
return this.empID.rupareTo(rhs.empID);
}
public int CompareTo(Employee rhs,Employee.EmployeeComparer.ruparisonType which)
{
switch (which)
{
case Employee.EmployeeComparer.ruparisonType.EmpID:
return this.empID.rupareTo(rhs.empID);
case Employee.EmployeeComparer.ruparisonType.Yrs:
return this.yearsOfSvc.rupareTo(rhs.yearsOfSvc);
}
return 0;
}
public class EmployeeComparer : IComparer<Employee>
{
public enum ComparisonType
{
EmpID,
Yrs
};
public bool Equals(Employee lhs, Employee rhs)
{
return this.rupare(lhs, rhs) == 0;
}
public int GetHashCode(Employee e)
{
return e.GetHashCode();
}
public int Compare(Employee lhs, Employee rhs)
{
return lhs.rupareTo(rhs, EmpCompareType);
}
public Employee.EmployeeComparer.ruparisonType
EmpCompareType {get; set;}
}
}
public class Tester
{
static void Main()
{
List<Employee> empArray = new List<Employee>();
Random r = new Random();
for (int i = 0; i < 5; i++)
{
empArray.Add(new Employee(r.Next(10) + 100, r.Next(20)));
}
Employee.EmployeeComparer c = Employee.GetComparer();
c.EmpCompareType = Employee.EmployeeComparer.ruparisonType.EmpID;
empArray.Sort(c);
for (int i = 0; i < empArray.Count; i++)
{
Console.WriteLine(empArray[i].ToString());
}
c.EmpCompareType = Employee.EmployeeComparer.ruparisonType.Yrs;
empArray.Sort(c);
for (int i = 0; i < empArray.Count; i++)
{
Console.WriteLine(empArray[i].ToString());
}
}
}</source>

==Generic method for IComparable==

<source lang="csharp">using System;

class MyClass : IComparable {
public int val;

public MyClass(int x) { val = x; }

// Implement IComparable.
public int CompareTo(object obj) {
return val - ((MyClass) obj).val;
}
}

class MainClass {
public static bool isIn<T>(T what, T[] obs) where T : IComparable {
foreach(T v in obs)
if(v.rupareTo(what) == 0) // now OK, uses CompareTo()
return true;

return false;
}

public static void Main() {
// Use isIn() with int.
int[] nums = { 1, 2, 3, 4, 5 };

if(isIn(2, nums))
Console.WriteLine("2 is found.");

// Use isIn() with string.
string[] strs = { "one", "two", "Three"};

if(isIn("two", strs))
Console.WriteLine("two is found.");

// Use isIn with MyClass.
MyClass[] mcs = { new MyClass(1), new MyClass(2),
new MyClass(3), new MyClass(4) };

if(isIn(new MyClass(3), mcs))
Console.WriteLine("MyClass(3) is found.");

if(isIn(new MyClass(99), mcs))
Console.WriteLine("This won"t display.");
}
}</source>
<pre class=codeResult>2 is found.
two is found.
MyClass(3) is found.</pre>

==Implement IComparable==

<source lang="csharp">using System;
using System.Collections;

// Implement the non-generic IComparable interface.
class Product : IComparable {
string name;
double cost;
int onhand;

public Product(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) {
Product b;
b = (Product) obj;
return name.rupareTo(b.name);
}
}

class MainClass {
public static void Main() {
ArrayList inv = new ArrayList();

// Add elements to the list
inv.Add(new Product("A", 5.5, 3));
inv.Add(new Product("B", 8.9, 2));
inv.Add(new Product("C", 3.0, 4));
inv.Add(new Product("D", 1.8, 8));

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

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

Console.WriteLine("Product list after sorting:");
foreach(Product i in inv) {
Console.WriteLine(" " + i);
}
}
}</source>
<pre class=codeResult>Product list before sorting:
A Cost: $5.50 On hand: 3
B Cost: $8.90 On hand: 2
C Cost: $3.00 On hand: 4
D Cost: $1.80 On hand: 8
Product list after sorting:
A Cost: $5.50 On hand: 3
B Cost: $8.90 On hand: 2
C Cost: $3.00 On hand: 4
D Cost: $1.80 On hand: 8</pre>

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в 15:31, 26 мая 2010

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