System.Random Class

public class Random

Base Types

Object
  Random

Assembly

mscorlib

Library

BCL

Summary

Generates psuedo-random numbers.

Description

Instances of this class are initialized using a "seed", or starting value. The series of numbers generated by instances of the class are repeatable: given the same seed value, all instances of this class generate the same series of numbers.

[Note: The numbers generated by this class are chosen with equal probability from a finite set of numbers. The numbers are generated by a definite mathematical algorithm and are therefore not truly random, but are sufficiently random for practical purposes. For this reason, the numbers are considered to be psuedo-random. ]

See Also

System Namespace

Members

Random Constructors

Random() Constructor
Random(int) Constructor

Random Methods

Random.Next(int) Method
Random.Next(int, int) Method
Random.Next() Method
Random.NextBytes Method
Random.NextDouble Method

This constructor is equivalent to Random(System.Environment.TickCount ).

[Note: When generating random numbers on high performance systems, the system clock value might not produce the desired behavior. For details, see the Random(Int32 ) constructor.]

See Also

System.Random Class, System Namespace

Seed

A Int32 used as the starting value for the pseudo-random number sequence.

Description

[Note: To construct instances that produce different random number sequences, invoke this constructor using different seed values such as might be produced by the system clock. Note, however that on high performance systems, the system clock might not change between invocations of the constructor, in which case the seed value will be the same for different instances of Random . When this is the case, additional operations are required to have the seed values differ in each invocation. ]

Example

The following example demonstrates using a bitwise complement operation to obtain different random numbers using a time-dependent seed value on high performance systems.

using System;
class RandomTest {
    public static void Main() {
        Random rand1 = new Random();
        Random rand2 = new Random(Environment.TickCount);
        Console.WriteLine("The random number is {0}",rand1.Next());
        Console.WriteLine("The random number is {0}",rand2.Next());

        Random rdm1 = new Random(unchecked(Environment.TickCount)); 
        Random rdm2 = new Random(~unchecked(Environment.TickCount)); 
        Console.WriteLine("The random number is {0}",rdm1.Next());
        Console.WriteLine("The random number is {0}",rdm2.Next());
    }
}
   

The output is

The random number is 1990211954

The random number is 1990211954

The random number is 1990211954

The random number is 964628126

See Also

System.Random Class, System Namespace

A Int32 set to a psuedo-random value greater than or equal to zero and less than maxValue. If maxValue is zero, returns zero.

Exceptions

Exception Type	Condition
ArgumentOutOfRangeException	maxValue is less than zero.

Description

[Behaviors: As described above.]

[Overrides: Override this method to customize the algorithm used to generate the return value.]

[Usage: Use this method to generate a psuedo-random number less than the specified maximum value.]

See Also

System.Random Class, System Namespace

System.Random Class, System Namespace

A Int32 greater than or equal to zero and less than System.Int32.MaxValue.

Description

[Behaviors: As described above.]

[Overrides: Override this method to customize the algorithm used to generate the return value.]

Example

The following example demonstrates using the Next method. The output generated by this example will vary.

using System;
class RandomTest {
    public static void Main() {
        Random rand1 = new Random();
        for (int i = 0; i<10;i++)
        Console.WriteLine("The random number is {0}",rand1.Next());
        
    }
}
   

The output is

The random number is 1544196111

The random number is 181749919

The random number is 1045210087

The random number is 1073826097

The random number is 1533078806

The random number is 1083151645

The random number is 569083504

The random number is 1711370568

The random number is 578178313

The random number is 409444742

See Also

System.Random Class, System Namespace

[Behaviors: 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 System.Byte.MaxValue.]

[Overrides: Override this method to customize the algorithm used to generate the return value.]

[Usage: Use the NextByte method to populate a Byte array with random numbers.]

See Also

System.Random Class, System Namespace

A Double greater than or equal to 0.0, and less than 1.0.

Description

[Behaviors: As described above.]

[Usage: Use this method to generate a psuedo-random number greater than or equal to zero, and less than one.]

Library

ExtendedNumerics

See Also

System.Random Class, System Namespace