生成随机数错误[关闭]

Question

I am testing a php function i found on the php documentation based on this comment: http://www.php.net/manual/en/function.rand.php#108861

<?php

    function RandNumber($e) {

        for ($i = 0; $i < $e; $i++) {
            $rand =  $rand .  rand(0, 9);  
        }
        return $rand;
    }

    echo RandNumber(4);
    // Outputs a 6 digit random number
?>

I get the error Notice:

Undefined variable: rand in /var/www/eod.php on line 7

This is line 7:

$rand =  $rand . rand(0, 9);

Why is causing this error since the function works as expected?

Answer 1

Initialize your $rand variable to remove this warning :

 function RandNumber($e){
     $rand="";
     for($i=0;$i<$e;$i++){
        $rand =  $rand.rand(0, 9);  
     }
     return $rand;
 }

Note that you may simplify your code :

 function RandNumber($e){
     $rand="";
     for(;$e-->0;){ // no need for an additional variable
        $rand .= rand(0, 9); // addition and assignement with one operator  
     }
     return $rand;
 }