php生成自定义长度随机字符串步骤详解

//随机生成字符串
function random($length) {
     srand(date("s"));
     $possible_charactors = "0123456789abcdefghijklmnopqrstuvwxyz";
     $string = "";
     while(strlen($string)<$length) {
          $string .= substr($possible_charactors,(rand()%(strlen($possible_charactors))),1);
     }
     return($string);
}

<?php
/*
* array unique_rand( int $min, int $max, int $num )
* 生成一定数量的不重复随机数
* $min 和 $max: 指定随机数的范围
* $num: 指定生成数量
*/ www.jbxue.com
function unique_rand($min, $max, $num) {
    $count = 0;
    $return = array();
    while ($count < $num) {
        $return[] = mt_rand($min, $max);
        $return = array_flip(array_flip($return));
        $count = count($return);
    }
    shuffle($return);
    return $return;
}
$arr = unique_rand(1, 25, 16);
sort($arr);
$result = '';
for($i=0; $i < count($arr);$i++)
{
 $result .= $arr[$i].',';
}
$result = substr($result, 0, -1);
echo $result;
?>