Summary and answers to frequently asked questions about learning dynamic webpage PHP technology_PHP tutorial

1: Why can’t I get the variable

I POST data name from one web page to another web page, why can’t I get any value when I output $name?

In PHP4.2 and later versions, reGISter_global defaults to off
If you want to get variables submitted from another page:

Method 1: Find register_global in PHP.ini and set it to on.
Method 2: Put this extract($_POST);extract($_GET); at the front of the receiving web page (note that there must be Session_Start() before extract($_SESSION)).
Method 3: Read the variables $a=$_GET["a"];$b=$_POST["b"] one by one. Although this method is troublesome, it is safer.

2: Debug your program

The value of a variable must be known at runtime. This is what I did, create a file debug.php with the following content:

PHP code:

Ob_Start();
Session_Start();
Echo "

";<br>
<br>
Echo "The _GET variables obtained on this page are:";<br>
Print_R($_GET);<br>
<br>
Echo "The _POST variables obtained on this page are:";<br>
Print_R($_POST);<br>
<br>
Echo "The _COOKIE variables obtained on this page are:";<br>
Print_R($_COOKIE);<br>
<br>
Echo "The _SESSION variables obtained on this page are:";<br>
Print_R($_SESSION);<br>
<br>
Echo "

";
?>

Then set: include_path = "c:/php" in php.ini, and put debug.php in this folder. You can include this file in every web page in the future and view the obtained variable names and values.

3: How to use session

For anything related to session, the function session_start() must be called before;

Paying value for a session is very simple, such as:

PHP code:

Session_start();
$Name = "This is a Session example";
Session_Register("Name");//Note, do not write: Session_Register("$Name");
Echo $_SESSION["Name"];
//Then $_SESSION["Name"] is "This is a Session example"
?>

After php4.2, you can pay directly for the session:

PHP code:

Session_Start();
$_SESSION["name"]="value";
?>

You can cancel the session like this:

PHP code:

session_start();
session_unset();
session_destroy();
?>

There is a bug in canceling a certain session variable in php4.2 and above.