PHP随机获得字符代码

<?php
//获取随机字符 此函数区分字符大小写 如果不区分大小写可加入函数strtolower
function genRandomString($len)
{
$chars = array(
"a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k"
"l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v"
"w" "x" "y" "z" "A" "B" "C" "D" "E" "F" "G"
"H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R"
"S" "T" "U" "V" "W" "X" "Y" "Z" "" "" ""
"" "" "" "" "" "" ""
);
$charsLen = count($chars) ;
shuffle($chars);// 将数组打乱
$output = "";
for ($i=; $i<$len; $i++)
{
$output = $chars[mt_rand( $charsLen)]; //获得一个数组元素
}
return $output;
}
$str = genRandomString();
echo $str;
?>