gistfile1.php

<?php
/**
 *  random_string
 *
 *	Generates random string based on character pool and length.
 *
 *	@param string $type Return string type.
 *	@param int $length Return string length.
 *
 *	@return string
 */
function random_string(String $type = null, Integer $length = null) {

	// Set default type value
	if(is_null($type) === true) {

		$type = 'alnum';

	}

	// Set default length value
	if(is_null($length) === true) {

		$length = 0;

	}

	// Unique random string
	$char_pool_unique = sha1(uniqid(mt_rand()));

	// Numeric characters
	$char_pool_numeric = '0123456789';

	// Numeric character without zeroes
	$char_pool_nozero = substr($char_pool_numeric, 1);

	// Lowercase alphabetic characters
	$char_pool_alpha = 'abcdefghijklmnopqrstuvwxyz';

	// Uppercase alphabetic characters
	$char_pool_alpha_uppercase = strtoupper($char_pool_alpha);

	// Salt characters
	$char_pool_salt = '!@#$%^&*()_+=-{}][;";/?<>.,';

	// Create unique string
	if($type === 'unique') {

		return $char_pool_unique;

	} else {

		// Handle character pools
		switch ($type) {

			case 'alnum' :

				$char_pool = $char_pool_alpha . $char_pool_alpha_uppercase . $char_pool_numeric;

			break;

			case 'alnum.lowercase' :

				$char_pool = $char_pool_alpha . $char_pool_numeric;

			break;

			case 'alnum.uppercase' :

				$char_pool = $char_pool_alpha_uppercase . $char_pool_numeric;

			break;

			case 'numeric' :

				$char_pool = $char_pool_numeric;

			break;

			case 'numeric.nozero' :

				$char_pool = $char_pool_nozero;

			break;

			case 'salt' :

				$char_pool = $char_pool_unique. $char_pool_salt;

			break;

		}

		$random_string = '';

		// Generate random string based on char pool
		for($n = 0; $n < $length; $n++) {

			$random_string .= substr($char_pool, mt_rand(0, strlen($char_pool) -1), 1);

		}

		return $random_string;

	}

}
?>