question about sessions

jreider

on one server I have PHP 4.3.3 installed and my code works fine. What I'm doing is setting some $_SESSION variables on one page, then jumping to another using header("Location:........")

in PHP 4.3.3 I get no errors when attempting to use the session vars that were registered in the first page on the destination page

in PHP 4.3.4, with the exact same code, I get Undefined index: errors when attempting to use the previously declared session vars.. Any ideas?

ie:

session_start();
$_SESSION['var1']="";

header("Location:http://whatever.com");
exit;

then when "whatever.com" loads, I get errors in 4.3.4, but not in 4.3.3 with the identical code.. any suggestions would be greatly appreciated!

Jon

stolzyboy

what code is there at whatever.com?

jreider

"whatever.com" is a little upload page that has a form with 4 fields... I have an 'if' statement that checks to see if a field was left blank, and if so, display an error.

for example:

if ($_SESSION['missing_email']==""){

echo "You did not enter an email address"

$_SESSION['missing_email']=""; //reset to null for next attemp

}

so when a user goes to the site, they hit the page that sets the session vars first, then that shoots them to the next page (whatever.com) where they attempt to upload to the server. If something is left blank, the final script sends them back to 'whatever.com'.

Another oddity is that when the page initially loads, I get the Undefined index: errors, but if I refresh it, they go away.. I was just curious if anyone has encountered any SESSION issues with the 4.3.4 version?

jreider

ok, I just wrote a tiny little tester script that performs the same basic deal

page one: sets the session variable and redirects via header to page two

page two:

if ($_SESSION['testing']==""){

$_SESSION['testing']="a-ok";

}

echo $_SESSION['testing'];

I still get the 'undefined index: testing' error, BUT it still echoes the correct value below it.. Is it an error display issue perhaps?

stolzyboy

well in that example, depending on what PHP has for [man]error_reporting[/man] it may spit out an error, cuz you are checking if on that variable, but it hasn't been set to anything...

jreider

I've had no problems in settiong $_SESSION vars = "" with 4.3.3 - technically it is equal to "nothing", but it's set to at least "", you know? I'll look into the error reporting angle, I just hate to think that I'm hiding big errors by turning the error reporting down 🙂
thanks for looking into it!

Jon

swr

"" and null are not the same thing. "" is a zero-length string. Null is the complete lack of any string or other value.

In a string context null sometimes magicly transforms into "", but if your error reporting is set strict this will generate a warning.

If you want to check for actual unset values, the correct thing to use is isset($variable). If you want to check for unset values or emtpy string, use empty($variable).

Some versions of PHP with strict error handling enabled will give a warning when you access an array index that has not been set. So you may be able to use "if ($variable == null) ..." you can't use "if ($varaible['index'] == null) ..." because you will get a warning at the lack of an 'index' entry in the variable. Again, isset/empty is your friend.

I recomment using E_ALL error reporting, and using isset/emtpy to check your variables. This can help catch bugs early, which results in more robust code with less debugging time.

planetsim

dont set an array to null ($_SESSION) is a form of a array.

You must unset it

not like this though

unset($SESSION) that will unset $SESSION and will not be able to be used.

but like this

unset($_SESSSION['myindex']);

jreider

thanks a bunch, those are both ideas that I will try!

Jon