Checking if a session is active - php

Question

I am building a captcha class. I need to store the generated code in a PHP session. This is my code so far:
<?php
class captcha
{
private $rndStr;
private $length;
function generateCode($length = 5)
{
$this->length = $length;
$this->rndStr = md5(time() . rand(1, 1000));
$this->rndStr = substr($rndStr, 0, $this->length);
if(session_id() != '')
{
return "session active";
} else {
return "no session active";
}
}
}
?>
And using this code to check:
<?php
include('captcha.class.php');
session_start();
$obj = new captcha();
echo $obj->generateCode();
?>
But it doesn't output anything to the page, not even a PHP error. Does someone know why this is? And is there a better way I can check if I've started a session using session_start()?
Thanks.

Answer 1

$this->rndStr = substr($rndStr, 0, $this->length);
return $rndStr; //You return before the if statement is processed
if(session_id() != '')
{
return "session active";
} else {
return "no session active";
}
Answer in commented code above
Edit: And you changed your question and removed the return line, not nice for people bothering to answer :)

Answer 2

i was testing your class, seems ok here, got session active on page, maybe you want to try this line :
include(dirname(__FILE__).'/captcha.class.php');

Answer 3

You do have an error, so I suggest checking your error reporting level and display errors setting - lots of short tutorials on how to do that.
Notice: Undefined variable: rndStr in
/home/eric/localhost/test.php on line
12
Of course this is because you wrote $rndStr instead of $this->rndStr.
When I ran your code, aside from the error, I saw the expected output.
session active
Are you able to successfully output to the browser in other scripts?