Type: System.Random

System.Random Class

Assembly: Mscorlib.dll
Namespace: System

Summary: Represents a pseudo-random number generator, a device that produces a sequence of numbers that meet certain statistical requirements for randomness.

C# Syntax:

[Serializable]
public class Random

Remarks

Pseudo-random numbers are chosen with equal probability from a finite set of numbers. The chosen numbers are not completely random because a definite mathematical algorithm is used to select them, but they are sufficiently random for practical purposes.

The random number generation starts from a seed value. If the same seed is used repeatedly, the same series of numbers is generated. One way to produce different sequences is to make the seed value time-dependent, thereby producing a different series with each new instance of Random.

See also:

System Namespace

System.Random Member List:

Public Constructors

ctor #1	Overloaded: `.ctor()`Default constructor. This constructor is called by derived class constructors to initialize state in this type. Initializes a new instance of the Random class, using a time-dependent default seed value.
ctor #2	Overloaded: `.ctor(int Seed)` Initializes a new instance of the Random class, using the specified seed value.

Public Methods

Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
Next	Overloaded: `Next()` Returns a positive random number.
Next	Overloaded: `Next(int maxValue)` Returns a positive random number less than the specified maximum.
Next	Overloaded: `Next(int minValue, int maxValue)` Returns a random number within a specified range.
NextBytes	Fills the elements of a specified array of bytes with random numbers.
NextDouble	Returns a random number between 0.0 and 1.0.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.
Sample	Returns a random number between 0.0 and 1.0.

Hierarchy:

System.Object

System.Random

System.Random Member Details

Overloaded ctor #1

Summary: Initializes a new instance of the Random class, using a time-dependent default seed value.

Default constructor. This constructor is called by derived class constructors to initialize state in this type.

C# Syntax:


            public Random();

Remarks

The distribution of the generated numbers is uniform; each number is equally likely to be returned.

When generating random numbers on high-performance systems, the system clock value might not produce the expected behavior. For details, see the Remarks section of the ( Int32) constructor.

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Overloaded ctor #2

Summary: Initializes a new instance of the Random class, using the specified seed value.

C# Syntax:


            public Random(
   int Seed
);

Parameters:

Seed

A number used to calculate a starting value for the pseudo-random number sequence.

Remarks

If your application requires different random number sequences, invoke this constructor repeatedly with different seed values. One way to produce a unique seed value is to make it time-dependent. For example, derive the seed value from the system clock.

However, if your application runs on a fast computer the system clock might not have time to change between invocations of this constructor; the seed value might be the same for different instances of Random. In that case, apply an algorithm to differentiate the seed value in each invocation.

For instance, the following C# expressions use a bitwise complement operation to generate two different seed values even if the system time value is the same.

Random rdm1 = new Random(unchecked((int)DateTime.Now.Ticks));

Random rdm2 = new Random(~unchecked((int)DateTime.Now.Ticks));

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Method: Equals(
object obj
)

Inherited
See base class member description: System.Object.Equals

C# Syntax:


            public virtual bool Equals(
   object obj
);

For more information on members inherited from System.Object click on the link above.

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Method: Finalize()

Inherited
See base class member description: System.Object.Finalize

C# Syntax:


            ~Random();

For more information on members inherited from System.Object click on the link above.

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Method: GetHashCode()

Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:


            public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Method: GetType()

Inherited
See base class member description: System.Object.GetType

C# Syntax:


            public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Method: MemberwiseClone()

Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:


            protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Overloaded Method: Next()

Summary: Returns a positive random number.

C# Syntax:


            public virtual int Next();

Return Value:: A number greater than or equal to zero and less than Int32.MaxValue.

See also:
Int32

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Overloaded Method: Next(
int maxValue
)

Summary: Returns a positive random number less than the specified maximum.

C# Syntax:


            public virtual int Next(
   int maxValue
);

Parameters:

maxValue

The upper bound of the random number to be generated.maxValue must be greater than or equal to zero.

Return Value:: A number greater than or equal to zero, and less than maxValue.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	maxValue is less than zero.

See also:
Int32

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Overloaded Method: Next(
int minValue,
int maxValue
)

Summary: Returns a random number within a specified range.

C# Syntax:


            public virtual int Next(
   int minValue,
   int maxValue
);

Parameters:

minValue

The lower bound of the random number returned.

maxValue

The upper bound of the random number returned.maxValue must be greater than or equal to minValue.

Return Value:: A number greater than or equal to minValue and less than maxValue. If minValue equals maxValue, minValue is returned.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	minValue is greater than maxValue.

See also:
Int32

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Method: NextBytes(
byte[] buffer
)

Summary: Fills the elements of a specified array of bytes with random numbers.

C# Syntax:


            public virtual void NextBytes(
   byte[] buffer
);

Parameters:

buffer

An array of bytes to contain random numbers.

Exceptions

Exception Type	Condition
ArgumentNullException	buffer is null.

Remarks

Each element of the array of bytes is set to a random number greater than or equal to zero, and less than or equal to Byte.MaxValue.

Example

        Random rnd = new Random();
        Byte[] b = new Byte[10];
        rnd.NextBytes(b);
        Console.WriteLine("The Random bytes are: ");
        for (int i = 0; i < 10; i++) {
            Console.Write(i);  
            Console.Write(":");
            Console.WriteLine(b[i]);
        }

See also:
Byte

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Method: NextDouble()

Summary: Returns a random number between 0.0 and 1.0.

C# Syntax:


            public virtual double NextDouble();

Return Value:: A double-precision floating point number greater than or equal to 0.0, and less than 1.0.

Remarks

This method is the public version of the protected method, Random.Sample.

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Method: Sample()

Summary: Returns a random number between 0.0 and 1.0.

C# Syntax:


            protected virtual double Sample();

Return Value:: A double-precision floating point number greater than or equal to 0.0, and less than 1.0.

Remarks

Create a derived class of Random to override this method and produce a different distribution.

See also:
Random.NextDouble

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Method: ToString()

Inherited
See base class member description: System.Object.ToString

C# Syntax:


            public virtual string ToString();

For more information on members inherited from System.Object click on the link above.