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Chapter 3: ColdFusion Functions
Rand
Description
Generates a pseudo-random number.
Returns
A pseudo-random decimal number, in the range 0 – 1.
Category
Mathematical functions
,
Security functions
Function syntax
Rand
([
algorithm
])
History
ColdFusion MX 7: Added the
algorithm
parameter.
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>
<cfoutput>
<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).
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