php简单随机字符串生成方法示例

<?php
function rand_str($length,$p='all'){
 $nums = '0123456789';
 $lowers = 'abcdefghijklmnopqrstuvwxyz';
 $uppers = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 if ($p == 'all') {
 $src = $nums.$lowers.$uppers;
 } else {
 $src = '';
 if (strpos($p, 'num') !== false)
  $src .= $nums;
 if (strpos($p, 'lower') !== false)
  $src .= $lowers;
 if (strpos($p, 'upper') !== false)
  $src .= $uppers;
 }
 return $src? substr(str_shuffle($src), 0, $length) : $src;
}
?>

substr(str_shuffle($src), 0, $length)