[SOLVED] Uninitialized string offset issue

Hi guys,

i am having this issue wheras php outputs this error:

Notice: Uninitialized string offset: 36 in C:\Program Files\EasyPHP 3.0\www\register.php on line 73

now this is my code around line 73:

$captchars = '0123456789abcdefghijklmnopqrstuvwxyz';
$captchalength = rand(3, 5);
    $characters = $captchars;
//captcha string
$captstring = ""; 
    for ($p = 0; $p < $captchalength; $p++) {
        $captstring .= $characters[mt_rand(0, strlen($characters))];
    }
   $captchatext = $captstring;

i then have a captcha image generation scriptthat takes the variable "$captchatext" and makes it an image,

now this error only happens at some times and takes one letter off the string, it can also happen twice and take 2 letters, kinda annoying

thanks heaps

$captstring .= $characters[mt_rand(0, strlen($characters) - 1)];

are you able to explain why i need to take one off it please?

(this works perfectly btw thanks )

Because string indexes (like arrays) start at 0. So, if a string is 10 chars in length, the last letter will be indexed as 9.

okay, thanks i understand now, i never throught of that before xD

can you please make this resolved

You yourself need to mark it as resolved, the button is in the bottom left corner I believe.