php怎么实现数组随机且不重复

<?php
define('RANDOM_MAX', 100);
define('COUNT', 10);

echo 'max random num: '.RANDOM_MAX, ' ;result count:'.COUNT, '<br/>';

invoke_entry('rand1');
invoke_entry('rand2');
invoke_entry('rand3');
invoke_entry('rand4');

function invoke_entry($func_name) {
	$time = new time();
	$time->time_start();
	call_user_func($func_name);
	echo $func_name.' time spend: ', $time->time_spend();
	echo '<br/>';
}
function rand1() {
	$numbers = range (1, RANDOM_MAX);
	shuffle($numbers);	//随机打乱数组
	$result = array_slice($numbers, 1, COUNT);
	return $result;
}
function rand2() {
	$result = array(); 
	while(count($result)< COUNT) {
	$result[] = mt_rand(1, RANDOM_MAX);	//mt_rand()是比rand()更好更快的随机函数
	$result = array_unique($result); //删除数组中重复的元素
	}
	return $result;
}
function rand3() {
	$result = array(); 
	while(count($result) < COUNT) {
	$_tmp = mt_rand(1, RANDOM_MAX);
	if(!in_array($_tmp, $result)) {	//当数组中不存在相同的元素时，才允许插入
	$result[] = $_tmp;
	}
	} 
	return $result;
}
function rand4() {
	$result = array();
	while (count($result) < COUNT) {
	$result[] = mt_rand(1, RANDOM_MAX);
	$result = array_flip(array_flip($result));	//array_flip将数组的key和value交换
	}
	return $result;
}
class time {
	private $_start;
	
	public function time_start() {
	$this->_start = $this->microtime_float();
	}
	public function time_spend() {
	return $this->microtime_float() - $this->_start;
	}
	private function microtime_float() {
	list($usec, $sec) = explode(" ", microtime());
	return ((float)$usec + (float)$sec);
	}
}


?>