如何检查变量是否设置而不是NULL / Empty并将其保存以供下一页继续使用？

Question

I've got an application which has an embedded IE6 browser. On opening it inside the application, it sends a $_POST variable: $_POST['VARIABLE'].

What's the best way to check in the start of my script that if this variable isn't sent (security check to make sure it's opening only via the application) and save it to use it on the next page?

I use sessions on my website since I store account ids, email, password, so I believe I can use it to save this variable too. Please let me know.

Answer 1

You could do something like this:

if(!array_key_exists('VARIABLE',$_POST))
{
   //this variable is not set in post - proceed accordingly
}
else
{
  //value is sent from POST, lets put it in session if its not already there,
  //or if a previous POST value is still in session - lets update that
  if(!array_key_exists('VARIABLE',$_SESSION) || 
  $_SESSION['VARIABLE'] != $_POST['VARIABLE'])
  {
     $_SESSION['VARIABLE'] = $_POST['VARIABLE'];
  }
}

// ...in the rest of the code check $_SESSION['VARIABLE'] and act accordingly.