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  1. using System;
  2.  
  3. public class Test
  4. {
  5. 	public static void Main()
  6. 	{
  7. 		// 2,000,000,000/2,000,000,001
  8. 		Rational r = new Rational(2000000000, 2000000001);
  9. 		Console.WriteLine(r + r);
  10. 	}
  11. }
  12.  
  13. //namespace NotSystemAndOthersThingsThatIHaveNoPracticalUseFor
  14. //{
  15. 	// This is Version 2.
  16. 	public struct Rational : IComparable, IComparable<Rational>, IEquatable<Rational>
  17. 	{
  18. 		// Retained from Version 1.
  19. 		public int Numerator { get; private set; }
  20. 		public int Denominator { get; private set; }
  21.  
  22. 		// These fields bypass Simplify().
  23. 		public static readonly Rational MinValue = new Rational { Numerator = int.MinValue, Denominator = 1 };
  24. 		public static readonly Rational MaxValue = new Rational { Numerator = int.MaxValue, Denominator = 1 };
  25. 		public static readonly Rational Epsilon = new Rational { Numerator = 1, Denominator = int.MaxValue };
  26. 		public static readonly Rational Undefined = new Rational { Numerator = 0, Denominator = 0 };
  27. 		public static readonly Rational Zero = new Rational { Numerator = 0, Denominator = 1 };
  28. 		public static readonly Rational One = new Rational { Numerator = 1, Denominator = 1 };
  29. 		public static readonly Rational MinusOne = new Rational { Numerator = -1, Denominator = 1 };
  30.  
  31. 		public Rational(int numerator, int denominator = 1) : this()
  32. 		{
  33. 			Numerator = numerator;
  34. 			Denominator = denominator;
  35. 			// There is a special case where Simplify() could throw an exception:
  36. 			//
  37. 			//	  new Rational(int.MinValue, certainNegativeIntegers)
  38. 			//
  39. 			// In general, having the contructor throw an exception is bad practice.
  40. 			// However given the extremity of this special case and the fact that Rational 
  41. 			// is an immutable struct where its inputs are ONLY validated DURING
  42. 			// construction, I allow the exception to be thrown here.
  43. 			Simplify();
  44. 		}
  45.  
  46. 		public static bool TryCreate(int numerator, int denominator, out Rational result)
  47. 		{
  48. 			try
  49. 			{
  50. 				result = new Rational(numerator, denominator);
  51. 				return true;
  52. 			}
  53. 			catch
  54. 			{
  55. 				result = Undefined;
  56. 			}
  57. 			return false;
  58. 		}
  59.  
  60. 		public static bool TryParse(string s, out Rational result)
  61. 		{
  62. 			try
  63. 			{
  64. 				result = Rational.Parse(s);
  65. 				return true;
  66. 			}
  67. 			catch
  68. 			{
  69. 				result = Undefined;
  70. 			}
  71. 			return false;
  72. 		}
  73.  
  74. 		public static Rational Parse(string s)
  75. 		{
  76. 			// Note that "3 / -4" would return new Rational(-3, 4).
  77. 			var tokens = s.Split(new char[] { '/' });
  78.  
  79. 			var numerator = 0;
  80. 			var denominator = 0;
  81.  
  82. 			switch (tokens.Length)
  83. 			{
  84. 				case 1:
  85. 					numerator = GetInteger("Numerator", tokens[0]);
  86. 					denominator = 1;
  87. 					break;
  88. 				case 2:
  89. 					numerator = GetInteger("Numerator", tokens[0]);
  90. 					denominator = GetInteger("Denominator", tokens[1]);
  91. 					break;
  92. 				default:
  93. 					throw new ArgumentException(string.Format("Invalid input string: '{0}'", s));
  94. 			}
  95. 			return new Rational(numerator, denominator);
  96. 		}
  97.  
  98. 		// This is only called by Parse.
  99. 		private static int GetInteger(string desc, string s)
  100. 		{
  101. 			if (string.IsNullOrWhiteSpace(s))
  102. 			{
  103. 				throw new ArgumentNullException(desc);
  104. 			}
  105. 			var result = 0;
  106. 			// TODO: Decide whether it's good idea to convert " -  4" to "-4".
  107. 			s = s.Replace(" ", string.Empty);
  108. 			if (!int.TryParse(s, out result))
  109. 			{
  110. 				throw new ArgumentException(string.Format("Invalid value for {0}: '{1}'", desc, s));
  111. 			}
  112. 			return result;
  113. 		}
  114.  
  115. 		// Ver 2 Change: uses if's instead of switch(Denominator).  Should be easier for Sam The Maintainer.
  116. 		//TODO: consider other overloads of ToString().  Perhaps one to always display a division symbol.
  117. 		// For example, new Rational(0, 0).ToString() --> "0/0" instead of "Undefined", or
  118. 		//			  new Rational(5).ToString()	--> "5/1" instead of "5"
  119. 		public override string ToString()
  120. 		{
  121. 			if (IsUndefined) { return "Undefined"; }
  122. 			if (IsInteger) { return Numerator.ToString(); }
  123. 			return string.Format("{0}/{1}", Numerator, Denominator);
  124. 		}
  125.  
  126. 		public int CompareTo(object other)
  127. 		{
  128. 			if (other == null) { return 1; }
  129. 			if (other is Rational) { return CompareTo((Rational)other); }
  130. 			throw new ArgumentException("Argument must be Rational");
  131. 		}
  132.  
  133. 		public int CompareTo(Rational other)
  134. 		{
  135. 			if (IsUndefined)
  136. 			{
  137. 				// While IEEE decrees that floating point NaN's are not equal to each other,
  138. 				// I am not under any decree to adhere to that same specification for Rational.
  139. 				return other.IsUndefined ? 0 : -1;
  140. 			}
  141. 			if (other.IsUndefined) { return 1; }
  142. 			return ToDouble().CompareTo(other.ToDouble());
  143. 		}
  144.  
  145. 		public bool Equals(Rational other)
  146. 		{
  147. 			if (IsUndefined) { return other.IsUndefined; }
  148. 			return (Numerator == other.Numerator) && (Denominator == other.Denominator);
  149. 		}
  150.  
  151. 		public override bool Equals(object other)
  152. 		{
  153. 			if (other == null) { return false; }
  154. 			if (other is Rational) { return Equals((Rational)other); }
  155. 			throw new ArgumentException("Argument must be Rational");
  156. 		}
  157.  
  158. 		// Mofified code that was stolen from:
  159. 		// http://w...content-available-to-author-only...k.org/default.aspx/4@0/4@0/DEVDIV_TFS/Dev10/Releases/RTMRel/ndp/clr/src/BCL/System/Double@cs/1305376/Double@cs
  160. 		// The hashcode for a double is the absolute value of the integer representation of that double.
  161. //		[System.Security.SecuritySafeCritical]  // auto-generated
  162. //		public unsafe override int GetHashCode()
  163. //		{
  164. //			if (Numerator == 0)
  165. //			{
  166. //				// Ensure that 0 and -0 have the same hash code
  167. //				return 0;
  168. //			}
  169. //			double d = ToDouble();
  170. //			long value = *(long*)(&d);
  171. //			return unchecked((int)value) ^ ((int)(value >> 32));
  172. //		}
  173.  
  174. 		public static bool operator ==(Rational rat1, Rational rat2)
  175. 		{
  176. 			return rat1.Equals(rat2);
  177. 		}
  178.  
  179. 		public static bool operator !=(Rational rat1, Rational rat2)
  180. 		{
  181. 			return !rat1.Equals(rat2);
  182. 		}
  183.  
  184. 		// Version 2 Change for operators { +, -, *, / } :
  185. 		// Removed goofy call to Simplify() and rely upon constructor.
  186. 		// I use local variable n and d for better readability for Sam the Maintainer,
  187. 		// who's failing eyesight may miss a comma here and there.
  188.  
  189. 		public static Rational operator +(Rational rat1, Rational rat2)
  190. 		{
  191. 			if (rat1.IsUndefined || rat2.IsUndefined)
  192. 			{
  193. 				return Undefined;
  194. 			}
  195. 			var n = (rat1.Numerator * rat2.Denominator) + (rat1.Denominator * rat2.Numerator);
  196. 			var d = rat1.Denominator * rat2.Denominator;
  197. 			return new Rational(n, d);
  198. 		}
  199.  
  200. 		public static Rational operator -(Rational rat1, Rational rat2)
  201. 		{
  202. 			if (rat1.IsUndefined || rat2.IsUndefined)
  203. 			{
  204. 				return Undefined;
  205. 			}
  206. 			var n = (rat1.Numerator * rat2.Denominator) - (rat1.Denominator * rat2.Numerator);
  207. 			var d = rat1.Denominator * rat2.Denominator;
  208. 			return new Rational(n, d);
  209. 		}
  210.  
  211. 		public static Rational operator *(Rational rat1, Rational rat2)
  212. 		{
  213. 			if (rat1.IsUndefined || rat2.IsUndefined)
  214. 			{
  215. 				return Undefined;
  216. 			}
  217. 			var n = rat1.Numerator * rat2.Numerator;
  218. 			var d = rat1.Denominator * rat2.Denominator;
  219. 			return new Rational(n, d);
  220. 		}
  221.  
  222. 		public static Rational operator /(Rational rat1, Rational rat2)
  223. 		{
  224. 			if (rat1.IsUndefined || rat2.IsUndefined)
  225. 			{
  226. 				return Undefined;
  227. 			}
  228. 			// fixed math error from Version 1
  229. 			var n = rat1.Numerator * rat2.Denominator;
  230. 			var d = rat1.Denominator * rat2.Numerator;
  231. 			return new Rational(n, d);
  232. 		}
  233.  
  234. 		// Ver 2 Change: now void - no longer returns Rational.
  235. 		// The simplified Denominator will always be >= 0 for any Rational.
  236. 		// For a Rational to be negative, the simplified Numerator will be negative.
  237. 		// Thus a Rational(3, -4) would simplify to Rational(-3, 4).
  238. 		private void Simplify()
  239. 		{
  240. 			// These corner cases are very quick checks that means slightly longer code.
  241. 			// Yet I feel their explicit handling makes their logic more clear to future maintenance.
  242. 			// More importantly, it bypasses modulus and division when its not absolutely needed.
  243. 			if (IsUndefined)
  244. 			{
  245. 				Numerator = 0;
  246. 				return;
  247. 			}
  248. 			if (Numerator == 0)
  249. 			{
  250. 				Denominator = 1;
  251. 				return;
  252. 			}
  253. 			if (IsInteger)
  254. 			{
  255. 				return;
  256. 			}
  257. 			if (Numerator == Denominator)
  258. 			{
  259. 				Numerator = 1;
  260. 				Denominator = 1;
  261. 				return;
  262. 			}
  263. 			if (Denominator < 0)
  264. 			{
  265. 				// One special corner case when unsimplified Denominator is < 0 and Numerator equals int.MinValue.
  266. 				if (Numerator == int.MinValue)
  267. 				{
  268. 					ReduceOrThrow();
  269. 					return;
  270. 				}
  271. 				// Simpler and faster than mutiplying by -1
  272. 				Numerator = -Numerator;
  273. 				Denominator = -Denominator;
  274. 			}
  275. 			// We only perform modulus and division if we absolutely must.
  276. 			Reduce();
  277. 		}
  278.  
  279. 		private void Reduce()
  280. 		{
  281. 			// Reduce() is never called if Numerator or Denominator equals 0.
  282. 			var greatestCommonDivisor = GreatestCommonDivisor(Numerator, Denominator);
  283. 			Numerator /= greatestCommonDivisor;
  284. 			Denominator /= greatestCommonDivisor;
  285. 		}
  286.  
  287. 		// Ver 2 Change: now void - no longer returns Rational.
  288. 		// Very special one off case: only called when unsimplified Numerater equals int.MinValue and Denominator is negative.
  289. 		// Some combinations produce a valid Rational, such as Rational(int.MinValue, int.MinValue), equivalent to Rational(1).
  290. 		// Others are not valid, such as Rational(int.MinValue, -1) because the Numerator would need to be (int.MaxValue + 1).
  291. 		private void ReduceOrThrow()
  292. 		{
  293. 			try
  294. 			{
  295. 				Reduce();
  296. 			}
  297. 			catch
  298. 			{
  299. 				throw new ArgumentException(string.Format("Invalid Rational(int.MinValue, {0})", Denominator));
  300. 			}
  301. 		}
  302.  
  303. 		public bool IsUndefined { get { return (Denominator == 0); } }
  304.  
  305. 		public bool IsInteger { get { return (Denominator == 1); } }
  306.  
  307. 		public double ToDouble()
  308. 		{
  309. 			if (IsUndefined) { return double.NaN; }
  310. 			return (double)Numerator / (double)Denominator;
  311. 		}
  312.  
  313. 		// http://e...content-available-to-author-only...a.org/wiki/Euclidean_algorithm
  314. 		private static int GreatestCommonDivisor(int a, int b)
  315. 		{
  316. 			return (b == 0) ? a : GreatestCommonDivisor(b, a % b);
  317. 		}
  318.  
  319. 	} //end struct
  320.  
  321. //} //end namespace
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139397120/-389294899
https://ideone.com/mcryV8
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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