Minute paper for today: by e-mail please, I would
like to get an assessment of your web sites. So please
check the What's Due? and grade your own website based
on that; e-mail me the results (dgerman@indiana.edu)

Topic for the day: server-side state with PHP. 

   UW PICO(tm) 4.10            File: one.php                           

<form>
  Name: <input type="text" name="name"> <p>
  Age: <input type="text" name="age"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on. <p> 
  Press <input type="submit" name="what" value="Reset"> to reset.
</form>

We discussed GET, POST also the action attribute: 

<form action="http://silo.cs.indiana.edu:9306/0207/two.php"> 
  Name: <input type="text" name="name"> <p>
  Age: <input type="text" name="age"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on. <p> 
  Press <input type="submit" name="what" value="Reset"> to reset.
</form>

two.php looks like this: 

   UW PICO(tm) 4.10            File: two.php                           

Hello, how are you <? echo $name; ?> ? <p>

Are you really <? echo $age; ?> years old?

Now I decide to write three.php which combines the above two files. 

   UW PICO(tm) 4.10           File: three.php                          

<? if ($name) { ?>
Hello, how are you <? echo $name; ?> ? <p>

Are you really <? echo $age; ?> years old?
<?
   } else { ?>
     Welcome.
<?
   }
 ?>

<form>
  Name: <input type="text" name="name"> <p>
  Age: <input type="text" name="age"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on.
  <p> Press <input type="submit" name="what" value="Reset"> to reset.
</form>


Here's three.phps:

http://silo.cs.indiana.edu:9306/0207/three.phps

We can rewrite three.php like this: 

<? if ($name) {   
     $q1 = "Hello, how are you $name ? <p>";
     $q2 = "Are you really $age years old?";
   } else {
     $q1 = "Welcome.";
     $q2 = "";
   } 
 ?>  
     
<form>
  <?=$q1;?> <p>      
  <?=$q2;?> <p> <hr>      
  Name: <input type="text" name="name"> <p>
  Age: <input type="text" name="age"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on.
  <p> Press <input type="submit" name="what" value="Reset"> to reset.
</form>

Now we write a simple calculator: 

   UW PICO(tm) 4.10            File: four.php                          

<? if ($message) {
     $balance += $amount;
     $message = "Balance is now: $balance";
   } else {
     $balance = 0;
     $message = "Welcome, your balance is $balance";
   }
 ?>

<form>
  <?=$message?> <p>
  Amount: <input type="text" name="amount"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on.

  <input type="hidden" name="message" value="<?=$message?>">
  <input type="hidden" name="balance" value="<?=$balance?>">
</form>

Change this to use session variables, which brings up the topic:

<? session_start();

   if ($message) {
     $balance += $amount;
     $message = "Balance is now: $balance";
   } else {
     session_register("balance");
     session_register("message");
     $balance = 0;
     $message = "Welcome, your balance is $balance";
   }
 ?>

<form>
  <?=$message?> <p>
  Amount: <input type="text" name="amount"> <p>
  Press <input type="submit" name="what" value="Proceed"> to move on.
  
</form>

Sessions look like this: 

-bash-3.1$ cat sess_45cbda1b0085707bb0df62560e1aab1d 
balance|i:0;message|s:26:"Welcome, your balance is 0";-bash-3.1$ 
-bash-3.1$ cat sess_45cbda1b0085707bb0df62560e1aab1d 
balance|i:23;message|s:18:"Balance is now: 23";-bash-3.1$ 

We also discussed accidental reloads.