User Guide

802 Chapter 3: ColdFusion Functions

Rand

Description

Generates a pseudo-random number.

Returns

A pseudo-random decimal number, in the range 0 – 1.

See also

Randomize

, RandRange

Parameters

Usage

Call the Randomize function before calling this function to seed the random number generator.

Seeding the generator ensures that the

Rand function always generates the same sequence of

pseudo-random numbers. This behavior is useful if you must reproduce a pattern consistently.

ColdFusion MX 7 uses the Java Cryptography Extension (JCE) and installs a Sun Java 1.4.2

runtime that includes the Sun JCE default security provider. This provider includes the

algorithms listed in the Parameters section (except the default algorithm). The JCE framework

includes facilities for using other provider implementations; however, Macromedia cannot

provide technical support for third-party security providers.

Example

The following example uses the SHA1PRNG algorithm to generate a single random number:

<h3>Rand Example</h3>

<p>Rand("SHA1PRNG") returned: #Rand("SHA1PRNG")#</p>

<p><A HREF = "#CGI.SCRIPT_NAME#">Try again</A>

</cfoutput>

Parameter Description

algorithm (Optional) The algorithm to use to generated the random number. ColdFusion MX

installs a cryptography library with the following algorithms:

• CFMX_COMPAT: the algorithm used in ColdFusion MX (default).

• SHA1PRNG: generates a number using the Sun Java SHA1PRNG algorithm.

This algorithm provides greater randomness than the default algorithm

• IBMSecureRandom: for IBM WebSphere (IBM JVM does not support the

SHA1PRNG algorithm).