Planet CakePHP

Generating a random string is an incredibly common task, this function provides quick string generation with four available output types: alpha, numeric, alphanum and hexadec.

/**
* Generate and return a random string
*
* The default string returned is 8 alphanumeric characters.
*
* The type of string returned can be changed with the output parameter.
* Four types are available: alpha, numeric, alphanum and hexadec.
*
* If the output parameter does not match one of the above, then the string
* supplied is used.
*
* @author Aidan Lister
* @version 2.1.0
* @link http://aidanlister.com/repos/v/function.str_rand.php
* @param int $length Length of string to be generated
* @param string $seeds Seeds string should be generated from
*/
function str_rand($length = 8, $output = 'alphanum')
{
// Possible seeds
$outputs['alpha'] = 'abcdefghijklmnopqrstuvwqyz';
$outputs['numeric'] = '0123456789';
$outputs['alphanum'] = 'abcdefghijklmnopqrstuvwqyz0123456789';
$outputs['hexadec'] = '0123456789abcdef';

// Choose seed
if (isset($outputs[$output])) {
$output = $outputs[$output];
}

// Seed generator
list($usec, $sec) = explode(' ', microtime());
$seed = (float) $sec + ((float) $usec * 100000);
mt_srand($seed);

// Generate
$str = '';
$output_count = strlen($output);
for ($i = 0; $length > $i; $i++) {
$str .= $output{mt_rand(0, $output_count - 1)};
}

return $str;
}

A quick example:

// Simple
echo str_rand();

// Longer
echo str_rand(15);

// Really big number
echo str_rand(15, 'numeric');

// Custom seeds
echo str_rand(15, '01');

This would produce the following output:

m2dy5ofe
remdjynd47b66hq
504359393089603
111001110111101