PHP random string generator

Question

I'm trying to create a randomized string in PHP, and I get absolutely no output with this:

<?php     function RandomString()     {         $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';         $randstring = '';         for ($i = 0; $i < 10; $i++) {             $randstring = $characters[rand(0, strlen($characters))];         }         return $randstring;     }      RandomString();     echo $randstring; 

What am I doing wrong?

Answer 1

To answer this question specifically, two problems:

1. $randstring is not in scope when you echo it.
2. The characters are not getting concatenated together in the loop.

Here's a code snippet with the corrections:

function generateRandomString($length = 10) {     $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';     $charactersLength = strlen($characters);     $randomString = '';     for ($i = 0; $i < $length; $i++) {         $randomString .= $characters[rand(0, $charactersLength - 1)];     }     return $randomString; } 

Output the random string with the call below:

// Echo the random string. // Optionally, you can give it a desired string length. echo generateRandomString(); 

Please note that this generates predictable random strings. If you want to create secure tokens, see this answer.