Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / whidbey / NetFXspW7 / ndp / clr / src / BCL / System / Random.cs / 1 / Random.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== /*============================================================ ** ** Class: Random ** ** ** Purpose: A random number generator. ** ** ===========================================================*/ namespace System { using System; using System.Runtime.CompilerServices; using System.Globalization; [System.Runtime.InteropServices.ComVisible(true)] [Serializable()] public class Random { // // Private Constants // private const int MBIG = Int32.MaxValue; private const int MSEED = 161803398; private const int MZ = 0; // // Member Variables // private int inext, inextp; private int[] SeedArray = new int[56]; // // Public Constants // // // Native Declarations // // // Constructors // public Random() : this(Environment.TickCount) { } public Random(int Seed) { int ii; int mj, mk; //Initialize our Seed array. //This algorithm comes from Numerical Recipes in C (2nd Ed.) mj = MSEED - Math.Abs(Seed); SeedArray[55]=mj; mk=1; for (int i=1; i<55; i++) { //Apparently the range [1..55] is special (Knuth) and so we're wasting the 0'th position. ii = (21*i)%55; SeedArray[ii]=mk; mk = mj - mk; if (mk<0) mk+=MBIG; mj=SeedArray[ii]; } for (int k=1; k<5; k++) { for (int i=1; i<56; i++) { SeedArray[i] -= SeedArray[1+(i+30)%55]; if (SeedArray[i]<0) SeedArray[i]+=MBIG; } } inext=0; inextp = 21; Seed = 1; } // // Package Private Methods // /*====================================Sample==================================== **Action: Return a new random number [0..1) and reSeed the Seed array. **Returns: A double [0..1) **Arguments: None **Exceptions: None ==============================================================================*/ protected virtual double Sample() { //Including this division at the end gives us significantly improved //random number distribution. return (InternalSample()*(1.0/MBIG)); } private int InternalSample() { int retVal; int locINext = inext; int locINextp = inextp; if (++locINext >=56) locINext=1; if (++locINextp>= 56) locINextp = 1; retVal = SeedArray[locINext]-SeedArray[locINextp]; if (retVal<0) retVal+=MBIG; SeedArray[locINext]=retVal; inext = locINext; inextp = locINextp; return retVal; } // // Public Instance Methods // /*=====================================Next===================================== **Returns: An int [0..Int32.MaxValue) **Arguments: None **Exceptions: None. ==============================================================================*/ public virtual int Next() { return InternalSample(); } private double GetSampleForLargeRange() { // The distribution of double value returned by Sample // is not distributed well enough for a large range. // If we use Sample for a range [Int32.MinValue..Int32.MaxValue) // We will end up getting even numbers only. int result = InternalSample(); // Note we can't use addition here. The distribution will be bad if we do that. bool negative = (InternalSample()%2 == 0) ? true : false; // decide the sign based on second sample if( negative) { result = -result; } double d = result; d += (Int32.MaxValue - 1); // get a number in range [0 .. 2 * Int32MaxValue - 1) d /= 2*(uint)Int32.MaxValue - 1 ; return d; } /*=====================================Next===================================== **Returns: An int [minvalue..maxvalue) **Arguments: minValue -- the least legal value for the Random number. ** maxValue -- One greater than the greatest legal return value. **Exceptions: None. ==============================================================================*/ public virtual int Next(int minValue, int maxValue) { if (minValue>maxValue) { throw new ArgumentOutOfRangeException("minValue",String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_MinMaxValue"), "minValue", "maxValue")); } long range = (long)maxValue-minValue; if( range <= (long)Int32.MaxValue) { return ((int)(Sample() * range) + minValue); } else { return (int)((long)(GetSampleForLargeRange() * range) + minValue); } } /*=====================================Next===================================== **Returns: An int [0..maxValue) **Arguments: maxValue -- One more than the greatest legal return value. **Exceptions: None. ==============================================================================*/ public virtual int Next(int maxValue) { if (maxValue<0) { throw new ArgumentOutOfRangeException("maxValue", String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("ArgumentOutOfRange_MustBePositive"), "maxValue")); } return (int)(Sample()*maxValue); } /*=====================================Next===================================== **Returns: A double [0..1) **Arguments: None **Exceptions: None ==============================================================================*/ public virtual double NextDouble() { return Sample(); } /*==================================NextBytes=================================== **Action: Fills the byte array with random bytes [0..0x7f]. The entire array is filled. **Returns:Void **Arugments: buffer -- the array to be filled. **Exceptions: None ==============================================================================*/ public virtual void NextBytes(byte [] buffer){ if (buffer==null) throw new ArgumentNullException("buffer"); for (int i=0; i=56) locINext=1; if (++locINextp>= 56) locINextp = 1; retVal = SeedArray[locINext]-SeedArray[locINextp]; if (retVal<0) retVal+=MBIG; SeedArray[locINext]=retVal; inext = locINext; inextp = locINextp; return retVal; } // // Public Instance Methods // /*=====================================Next===================================== **Returns: An int [0..Int32.MaxValue) **Arguments: None **Exceptions: None. ==============================================================================*/ public virtual int Next() { return InternalSample(); } private double GetSampleForLargeRange() { // The distribution of double value returned by Sample // is not distributed well enough for a large range. // If we use Sample for a range [Int32.MinValue..Int32.MaxValue) // We will end up getting even numbers only. int result = InternalSample(); // Note we can't use addition here. The distribution will be bad if we do that. bool negative = (InternalSample()%2 == 0) ? true : false; // decide the sign based on second sample if( negative) { result = -result; } double d = result; d += (Int32.MaxValue - 1); // get a number in range [0 .. 2 * Int32MaxValue - 1) d /= 2*(uint)Int32.MaxValue - 1 ; return d; } /*=====================================Next===================================== **Returns: An int [minvalue..maxvalue) **Arguments: minValue -- the least legal value for the Random number. ** maxValue -- One greater than the greatest legal return value. **Exceptions: None. ==============================================================================*/ public virtual int Next(int minValue, int maxValue) { if (minValue>maxValue) { throw new ArgumentOutOfRangeException("minValue",String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_MinMaxValue"), "minValue", "maxValue")); } long range = (long)maxValue-minValue; if( range <= (long)Int32.MaxValue) { return ((int)(Sample() * range) + minValue); } else { return (int)((long)(GetSampleForLargeRange() * range) + minValue); } } /*=====================================Next===================================== **Returns: An int [0..maxValue) **Arguments: maxValue -- One more than the greatest legal return value. **Exceptions: None. ==============================================================================*/ public virtual int Next(int maxValue) { if (maxValue<0) { throw new ArgumentOutOfRangeException("maxValue", String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("ArgumentOutOfRange_MustBePositive"), "maxValue")); } return (int)(Sample()*maxValue); } /*=====================================Next===================================== **Returns: A double [0..1) **Arguments: None **Exceptions: None ==============================================================================*/ public virtual double NextDouble() { return Sample(); } /*==================================NextBytes=================================== **Action: Fills the byte array with random bytes [0..0x7f]. The entire array is filled. **Returns:Void **Arugments: buffer -- the array to be filled. **Exceptions: None ==============================================================================*/ public virtual void NextBytes(byte [] buffer){ if (buffer==null) throw new ArgumentNullException("buffer"); for (int i=0; i
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- counter.cs
- BaseTreeIterator.cs
- TranslateTransform3D.cs
- OneToOneMappingSerializer.cs
- NavigationWindow.cs
- InfoCardSymmetricAlgorithm.cs
- SequenceFullException.cs
- ServiceContractAttribute.cs
- Pen.cs
- Label.cs
- JsonFormatWriterGenerator.cs
- ReferenceSchema.cs
- OleDbWrapper.cs
- Aggregates.cs
- Script.cs
- BrowserDefinition.cs
- RetrieveVirtualItemEventArgs.cs
- WebPartTransformerCollection.cs
- DbSourceCommand.cs
- SchemaCollectionPreprocessor.cs
- Expressions.cs
- WinFormsComponentEditor.cs
- ClientCredentialsSecurityTokenManager.cs
- Manipulation.cs
- BaseCAMarshaler.cs
- AppDomainUnloadedException.cs
- FacetEnabledSchemaElement.cs
- ScopelessEnumAttribute.cs
- RootNamespaceAttribute.cs
- UnsafeNativeMethods.cs
- DecimalAnimationBase.cs
- XmlQualifiedNameTest.cs
- TouchPoint.cs
- BreakRecordTable.cs
- HeaderCollection.cs
- PositiveTimeSpanValidator.cs
- TableLayoutStyleCollection.cs
- EditorZone.cs
- BinHexDecoder.cs
- DbConnectionStringCommon.cs
- OracleNumber.cs
- NodeLabelEditEvent.cs
- PrivateFontCollection.cs
- TextRunProperties.cs
- ParallelSeparator.xaml.cs
- WebDisplayNameAttribute.cs
- CodeArrayIndexerExpression.cs
- PageCache.cs
- ParenthesizePropertyNameAttribute.cs
- HtmlInputFile.cs
- RegexTypeEditor.cs
- SqlDependencyListener.cs
- documentation.cs
- AsyncCompletedEventArgs.cs
- HttpListenerException.cs
- DataSourceControl.cs
- ScriptingAuthenticationServiceSection.cs
- GregorianCalendar.cs
- EventData.cs
- SmiRecordBuffer.cs
- AdornerPresentationContext.cs
- AttributeAction.cs
- CaseStatementSlot.cs
- SoapTypeAttribute.cs
- CodeGenerator.cs
- DBSchemaRow.cs
- PhysicalOps.cs
- TouchesCapturedWithinProperty.cs
- SettingsBase.cs
- MoveSizeWinEventHandler.cs
- ApplicationSecurityInfo.cs
- AuthenticationServiceManager.cs
- DefaultShape.cs
- IPEndPointCollection.cs
- CertificateElement.cs
- WebServiceData.cs
- BamlRecordReader.cs
- XappLauncher.cs
- LogicalExpr.cs
- Material.cs
- Compiler.cs
- XmlQueryOutput.cs
- UnsafeNativeMethods.cs
- InfiniteIntConverter.cs
- UnsafeNativeMethods.cs
- QilPatternFactory.cs
- XmlSchemaAny.cs
- Int32Converter.cs
- SmiEventSink.cs
- OracleConnection.cs
- NamespaceMapping.cs
- DataSourceSerializationException.cs
- Pen.cs
- ResourceContainer.cs
- TouchEventArgs.cs
- XmlElement.cs
- ErrorTolerantObjectWriter.cs
- MonitoringDescriptionAttribute.cs
- _NegoState.cs
- MemberDescriptor.cs