javascript conversion..chars.substring

Question

我正在尝试将下面的javascript代码转换为php。

function randomString(len) {
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmn opqrstuvwxyz";
    var string_length = len;
    var randomstring = '';
    for (var i = 0; i < string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum, rnum + 1);
    }

    return randomstring;
}

到目前为止我的php代码。编辑:下面的工作代码

     function randomString($len) {
        $chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
        $string_length = strlen($chars);
        $randomstring = '';
        for ($i = 0; $i< $len; $i++) {
         $rnum = rand(0,$string_length);
         $randomstring.= $chars[$rnum];
        }

        return $randomstring;
    }

echo randomString(16);

chars.substring( rnum，rnum+ 1 ) mean...how在php中能实现什么.我可以理解，它占用了$chars..but的特定字符，rnum+1是用来做什么的？

Answer 1

你这样做：

$randomstring .= substr($chars，$rnum，$rnum + 1)；

阅读文档