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
- ImagingCache.cs
- SynchronizedPool.cs
- AutoFocusStyle.xaml.cs
- AspNetCacheProfileAttribute.cs
- InputLanguageEventArgs.cs
- DynamicDataRouteHandler.cs
- CharacterString.cs
- DataGridViewCellStateChangedEventArgs.cs
- XPathDocumentBuilder.cs
- GradientSpreadMethodValidation.cs
- RoleService.cs
- TrackingProfileDeserializationException.cs
- DataGridTextColumn.cs
- HtmlTable.cs
- EncoderExceptionFallback.cs
- RuntimeResourceSet.cs
- TypeDescriptionProvider.cs
- WebPartsPersonalization.cs
- ApplicationException.cs
- MemberHolder.cs
- EventMetadata.cs
- RefType.cs
- StrokeNodeOperations.cs
- XmlMapping.cs
- SqlException.cs
- PopupControlService.cs
- SoapHttpTransportImporter.cs
- InkCanvas.cs
- ToolStripTemplateNode.cs
- ComboBoxAutomationPeer.cs
- SByteConverter.cs
- CompilerState.cs
- ClientTarget.cs
- ToolTip.cs
- UserPreferenceChangedEventArgs.cs
- InternalConfigSettingsFactory.cs
- BitmapCache.cs
- VersionPair.cs
- NestPullup.cs
- DispatchChannelSink.cs
- PowerStatus.cs
- SecondaryIndexDefinition.cs
- DriveInfo.cs
- ToolBarButton.cs
- AspNetSynchronizationContext.cs
- DataStreams.cs
- Rect.cs
- XNodeValidator.cs
- AssertFilter.cs
- PopupEventArgs.cs
- metadatamappinghashervisitor.cs
- webproxy.cs
- DetailsViewRow.cs
- SizeConverter.cs
- FrameSecurityDescriptor.cs
- Misc.cs
- ToolboxComponentsCreatingEventArgs.cs
- ParameterToken.cs
- Enum.cs
- LayoutEditorPart.cs
- HelpOperationInvoker.cs
- BitmapEffectDrawingContextState.cs
- ComponentRenameEvent.cs
- WindowsFormsLinkLabel.cs
- XPathChildIterator.cs
- Matrix3DConverter.cs
- StateChangeEvent.cs
- ClientSponsor.cs
- EncodingStreamWrapper.cs
- UIElementParagraph.cs
- ValidationHelper.cs
- NavigatorInput.cs
- ParseChildrenAsPropertiesAttribute.cs
- HttpHandlerAction.cs
- SoapElementAttribute.cs
- ComponentCollection.cs
- XmlUrlResolver.cs
- ProtocolsConfigurationEntry.cs
- DSACryptoServiceProvider.cs
- ToolStripOverflow.cs
- TypeDependencyAttribute.cs
- XmlWriter.cs
- LongValidator.cs
- RectangleHotSpot.cs
- Logging.cs
- LassoSelectionBehavior.cs
- RuleInfoComparer.cs
- TreeNodeEventArgs.cs
- HttpServerVarsCollection.cs
- FixedPosition.cs
- SaveLedgerEntryRequest.cs
- Message.cs
- Policy.cs
- CharAnimationUsingKeyFrames.cs
- InstanceOwnerQueryResult.cs
- NativeBuffer.cs
- DataGridViewImageCell.cs
- FileDialog.cs
- InvalidDataException.cs
- InfiniteTimeSpanConverter.cs