Articolo
11/18/2011

VBMath.Randomize Method (Double)

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Initializes the random-number generator.

Namespace: Microsoft.VisualBasic
Assembly: Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

Syntax

'Declaration
Public Shared Sub Randomize ( _
    Number As Double _
)

public static void Randomize(
    double Number
)

Parameters

Number
Type: System.Double
Optional. An Object or any valid numeric expression.

Remarks

Randomize uses Number to initialize the Rnd function's random-number generator, giving it a new seed value. If you omit Number, the value returned by the system timer is used as the new seed value.

If Randomize is not used, the Rnd function (with no arguments) uses the same number as a seed the first time it is called, and thereafter uses the last-generated number as a seed value.

Note:
To repeat sequences of random numbers, call Rnd with a negative argument immediately before using Randomize with a numeric argument. Using Randomize with the same value for Number does not repeat the previous sequence.

Security Note:
Because the Random statement and the Rnd function start with a seed value and generate numbers that fall within a finite range, the results may be predictable by someone who knows the algorithm used to generate them. Consequently, the Random statement and the Rnd function should not be used to generate random numbers for use in cryptography. For more information, see RandomNumberGenerator.

Examples

This example uses the Randomize statement to initialize the random-number generator. Because the number argument has been omitted, Randomize uses the return value from the Timer function as the new seed value.

' Initialize the random-number generator.
Randomize()
' Generate random value between 1 and 6.
Dim value As Integer = CInt(Int((6 * Rnd()) + 1))

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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