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  1. // Licensed to the .NET Foundation under one or more agreements.
  2. // The .NET Foundation licenses this file to you under the MIT license.
  3. // See the LICENSE file in the project root for more information.
  4.  
  5. /*============================================================
  6. **
  7. **
  8. **
  9. ** Purpose: A random number generator.
  10. **
  11. ** 
  12. ===========================================================*/
  13. namespace System {
  14.  
  15.     using System;
  16.     using System.Runtime;
  17.     using System.Runtime.CompilerServices;
  18.     using System.Globalization;
  19.     using System.Diagnostics.Contracts;
  20. [System.Runtime.InteropServices.ComVisible(true)]
  21.     [Serializable]
  22.     public class Random {
  23.       //
  24.       // Private Constants 
  25.       //
  26.       private const int MBIG =  Int32.MaxValue;
  27.       private const int MSEED = 161803398;
  28.       private const int MZ = 0;
  29.  
  30.  
  31.       //
  32.       // Member Variables
  33.       //
  34.       private int inext;
  35.       private int inextp;
  36.       private int[] SeedArray = new int[56];
  37.  
  38.       //
  39.       // Public Constants
  40.       //
  41.  
  42.       //
  43.       // Native Declarations
  44.       //
  45.  
  46.       //
  47.       // Constructors
  48.       //
  49.  
  50.       public Random() 
  51.         : this(Environment.TickCount) {
  52.       }
  53.  
  54.       public Random(int Seed) {
  55.         int ii;
  56.         int mj, mk;
  57.  
  58.         //Initialize our Seed array.
  59.         int subtraction = (Seed == Int32.MinValue) ? Int32.MaxValue : Math.Abs(Seed);
  60.         mj = MSEED - subtraction;
  61.         SeedArray[55]=mj;
  62.         mk=1;
  63.         for (int i=1; i<55; i++) {  //Apparently the range [1..55] is special (Knuth) and so we're wasting the 0'th position.
  64.           ii = (21*i)%55;
  65.           SeedArray[ii]=mk;
  66.           mk = mj - mk;
  67.           if (mk<0) mk+=MBIG;
  68.           mj=SeedArray[ii];
  69.         }
  70.         for (int k=1; k<5; k++) {
  71.           for (int i=1; i<56; i++) {
  72.         SeedArray[i] -= SeedArray[1+(i+30)%55];
  73.         if (SeedArray[i]<0) SeedArray[i]+=MBIG;
  74.           }
  75.         }
  76.         inext=0;
  77.         inextp = 21;
  78.         Seed = 1;
  79.       }
  80.  
  81.       //
  82.       // Package Private Methods
  83.       //
  84.  
  85.       /*====================================Sample====================================
  86.       **Action: Return a new random number [0..1) and reSeed the Seed array.
  87.       **Returns: A double [0..1)
  88.       **Arguments: None
  89.       **Exceptions: None
  90.       ==============================================================================*/
  91.       protected virtual double Sample() {
  92.           //Including this division at the end gives us significantly improved
  93.           //random number distribution.
  94.           return (InternalSample()*(1.0/MBIG));
  95.       }
  96.  
  97.       private int InternalSample() {
  98.           int retVal;
  99.           int locINext = inext;
  100.           int locINextp = inextp;
  101.  
  102.           if (++locINext >=56) locINext=1;
  103.           if (++locINextp>= 56) locINextp = 1;
  104.  
  105.           retVal = SeedArray[locINext]-SeedArray[locINextp];
  106.  
  107.           if (retVal == MBIG) retVal--;          
  108.           if (retVal<0) retVal+=MBIG;
  109.  
  110.           SeedArray[locINext]=retVal;
  111.  
  112.           inext = locINext;
  113.           inextp = locINextp;
  114.  
  115.           return retVal;
  116.       }
  117.  
  118.       //
  119.       // Public Instance Methods
  120.       // 
  121.  
  122.  
  123.       /*=====================================Next=====================================
  124.       **Returns: An int [0..Int32.MaxValue)
  125.       **Arguments: None
  126.       **Exceptions: None.
  127.       ==============================================================================*/
  128.       public virtual int Next() {
  129.         return InternalSample();
  130.       }
  131.  
  132.       private double GetSampleForLargeRange() {
  133.           // The distribution of double value returned by Sample 
  134.           // is not distributed well enough for a large range.
  135.           // If we use Sample for a range [Int32.MinValue..Int32.MaxValue)
  136.           // We will end up getting even numbers only.
  137.  
  138.           int result = InternalSample();
  139.           // Note we can't use addition here. The distribution will be bad if we do that.
  140.           bool negative = (InternalSample()%2 == 0) ? true : false;  // decide the sign based on second sample
  141.           if( negative) {
  142.               result = -result;
  143.           }
  144.           double d = result;
  145.           d += (Int32.MaxValue - 1); // get a number in range [0 .. 2 * Int32MaxValue - 1)
  146.           d /= 2*(uint)Int32.MaxValue - 1  ;              
  147.           return d;
  148.       }
  149.  
  150.  
  151.       /*=====================================Next=====================================
  152.       **Returns: An int [minvalue..maxvalue)
  153.       **Arguments: minValue -- the least legal value for the Random number.
  154.       **           maxValue -- One greater than the greatest legal return value.
  155.       **Exceptions: None.
  156.       ==============================================================================*/
  157.       public virtual int Next(int minValue, int maxValue) {
  158.           if (minValue>maxValue) {
  159.               throw new ArgumentOutOfRangeException("minValue",Environment.GetResourceString("Argument_MinMaxValue", "minValue", "maxValue"));
  160.           }
  161.           Contract.EndContractBlock();
  162.  
  163.           long range = (long)maxValue-minValue;
  164.           if( range <= (long)Int32.MaxValue) {  
  165.               return ((int)(Sample() * range) + minValue);
  166.           }          
  167.           else { 
  168.               return (int)((long)(GetSampleForLargeRange() * range) + minValue);
  169.           }
  170.       }
  171.  
  172.  
  173.       /*=====================================Next=====================================
  174.       **Returns: An int [0..maxValue)
  175.       **Arguments: maxValue -- One more than the greatest legal return value.
  176.       **Exceptions: None.
  177.       ==============================================================================*/
  178.       public virtual int Next(int maxValue) {
  179.           if (maxValue<0) {
  180.               throw new ArgumentOutOfRangeException("maxValue", Environment.GetResourceString("ArgumentOutOfRange_MustBePositive", "maxValue"));
  181.           }
  182.           Contract.EndContractBlock();
  183.           return (int)(Sample()*maxValue);
  184.       }
  185.  
  186.  
  187.       /*=====================================Next=====================================
  188.       **Returns: A double [0..1)
  189.       **Arguments: None
  190.       **Exceptions: None
  191.       ==============================================================================*/
  192.       public virtual double NextDouble() {
  193.         return Sample();
  194.       }
  195.  
  196.  
  197.       /*==================================NextBytes===================================
  198.       **Action:  Fills the byte array with random bytes [0..0x7f].  The entire array is filled.
  199.       **Returns:Void
  200.       **Arugments:  buffer -- the array to be filled.
  201.       **Exceptions: None
  202.       ==============================================================================*/
  203.       public virtual void NextBytes(byte [] buffer){
  204.         if (buffer==null) throw new ArgumentNullException("buffer");
  205.         Contract.EndContractBlock();
  206.         for (int i=0; i<buffer.Length; i++) {
  207.           buffer[i]=(byte)(InternalSample()%(Byte.MaxValue+1)); 
  208.         }
  209.       }
  210.     }
  211.  
  212.  
  213.  
  214. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
prog.cs(159,76): error CS0122: `System.Environment.GetResourceString(string, params object[])' is inaccessible due to its protection level
/usr/lib/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
prog.cs(180,77): error CS0122: `System.Environment.GetResourceString(string, params object[])' is inaccessible due to its protection level
/usr/lib/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
error CS5001: Program `prog.exe' does not contain a static `Main' method suitable for an entry point
Compilation failed: 3 error(s), 0 warnings
stdout 
Standard output is empty
https://ideone.com/hytuhr
Random
language:
C# (gmcs 5.20.1)
created:
8 years ago
visibility:
public

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