PHP中怎么产生不重复随机数

<span><?php $numbers = range (1,50); <span>//shuffle 将数组顺序随即打乱 </span> shuffle ($numbers); <span>//array_slice 取该数组中的某一段 </span> $num=6; 
$result = array_slice($numbers,0,$num); 
print_r($result); 
?>

<span><?php $numbers = range (1,20); <span>//播下随机数发生器种子，可有可无，测试后对结果没有影响</span> srand ((<span>float</span>)microtime()*1000000); 
shuffle ($numbers); <span>//跳过list第一个值（保存的是索引）</span> <span>while</span> (<span>list</span>(, $number) = each ($numbers)) { <span>echo</span> <span>"$number "</span>; 
} 
?>

<span><?php <span>function</span> NoRand($begin=0,$end=20,$limit=5){ 
$rand_array=range($begin,$end); 
shuffle($rand_array);<span>//调用现成的数组随机排列函数 </span> <span>return</span> array_slice($rand_array,0,$limit);<span>//截取前$limit个 </span> } 
print_r(NoRand()); 
?>

<span><?php $tmp=<span>array</span>(); <span>while</span>(count($tmp)

<span><?php $tmp = range(1,30);
print_r(array_rand($tmp,10));
?></span>