book iequatable, C#

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//Title of this code
//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
	
	class MyClass : IComparable<MyClass>, IEquatable<MyClass> 
	{

public int Val;

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

// Implement IComparable<T>.

public int CompareTo(MyClass other) 
		{

return Val - other.Val; // Now, no cast is needed.

}

// Implement IEquatable<T>.

public bool Equals(MyClass other) 
		{

return Val == other.Val;

}

// An override of Equals(Object).

public override bool Equals(Object obj)
		{

if(obj is MyClass)

return Equals((MyClass) obj);

return false;

}
		// An override of GetHashCode().

public override int GetHashCode() 
		{

return Val.GetHashCode();

}

class CompareDemo
	{

// Require IEquatable<T> interface.

public static bool IsIn<T>(T what, T[] obs) where T : IEquatable<T> 
		{

foreach(T v in obs)

if(v.Equals(what)) // Uses Equals()

return true;

return false;

}

// Require IComparable<T> interface. This method assumes

// a sorted array. It returns true if what is inside the range

// of elements passed to obs.

public static bool InRange<T>(T what, T[] obs) where T : IComparable<T> 
		{

if(what.CompareTo(obs[0]) < 0 ||

what.CompareTo(obs[obs.Length-1]) > 0) return false;

return true;

}
	}
	public class Program
	{
		public static void Main(string[] args)
		{
			// Use IsIn() with int.

int[] nums = { 1, 2, 3, 4, 5 };

if(CompareDemo.IsIn(2, nums))

Console.WriteLine("2 is found.");

if(CompareDemo.IsIn(99, nums))

Console.WriteLine("This won’t display.");

// Use IsIn() with MyClass.

MyClass[] mcs = { new MyClass(1), new MyClass(2),

new MyClass(3), new MyClass(4) };

if(CompareDemo.IsIn(new MyClass(3), mcs))

Console.WriteLine("MyClass(3) is found.");

if(CompareDemo.IsIn(new MyClass(99), mcs))

Console.WriteLine("This won’t display.");

// Use InRange() with int.

if(CompareDemo.InRange(2, nums))
			Console.WriteLine("2 is within the range of nums.");

if(CompareDemo.InRange(1, nums))

Console.WriteLine("1 is within the range of nums.");

if(CompareDemo.InRange(5, nums))

Console.WriteLine("5 is within the range of nums.");

if(!CompareDemo.InRange(0, nums))

Console.WriteLine("0 is NOT within the range of nums.");

if(!CompareDemo.InRange(6, nums))

Console.WriteLine("6 is NOT within the range of nums.");

// Use InRange() with MyClass.

if(CompareDemo.InRange(new MyClass(2), mcs))

Console.WriteLine("MyClass(2) is within the range of mcs.");

if(CompareDemo.InRange(new MyClass(1), mcs))

Console.WriteLine("MyClass(1) is within the range of mcs.");

if(CompareDemo.InRange(new MyClass(4), mcs))

Console.WriteLine("MyClass(4) is within the range of mcs.");

if(!CompareDemo.InRange(new MyClass(0), mcs))

Console.WriteLine("MyClass(0) is NOT within the range of mcs.");

if(!CompareDemo.InRange(new MyClass(5), mcs))

Console.WriteLine("MyClass(5) is NOT within the range of mcs.");
		}
	}
}

Show compiler warnings [ + ] Show input
Compilation time: 0.08 sec, absolute running time: 0.09 sec, cpu time: 0.09 sec, average memory usage: 16 Mb, average nr of threads: 4