Classic: learning dynamic web page PHP skills common Title summary

1: Why can't I get the variable I post the data name to another webpage on one webpage? why can't I get any value when I output $ name? In versions later than PHP4.2, the default value of reGISter_global is off. if you want to get the variable submitted from another page: Method 1: in PHP. I

1: Why can't I get the variable?

Why can't I get any value when I output $ name when I POST data name to another webpage?

In versions later than PHP4.2, the default value of reGISter_global is off.
To get the variables submitted from another page:

Method 1: Find register_global in PHP. ini and set it to on.
Method 2: Put the extract ($ _ POST); extract ($ _ GET) at the top of the receiving webpage; (pay attention to extract ($ _ SESSION) session_Start () is required ()).
Method 3: Read the variable $ a =$ _ GET ['A']; $ B =$ _ POST ['B'] and so on one by one. this method is troublesome but safe.

2: debug your program

You must know the value of a variable at runtime. In this case, create a debug. php file with the following content:

PHP code:

<? PHP
Ob_Start ();
Session_Start ();
Echo '<pre> ';

Echo 'The _ GET variables obtained on this page are :';
Print_R ($ _ GET );

Echo 'The _ POST variables obtained on this page are :';
Print_R ($ _ POST );

Echo 'The COOKIE variables obtained on this page are :';
Print_R ($ _ COOKIE );

Echo 'The _ SESSION variables obtained on this page are :';
Print_R ($ _ SESSION );

Echo '</pre> ';
?>

Then in php. set in ini: export de_path = 'C:/php', and debug. php is placed in this folder, and you can include this file in each web page to view the variable name and value.

3: How to apply the session

All session-related functions must call session_start ();

It is very simple to pay for the session, such:

PHP code:

<? Php
Session_start ();
$ Name = 'This is a Session example ';
Session_Register ('name'); // do not write it as Session_Register ('$ name ');
Echo $ _ SESSION ['name'];
// After $ _ SESSION ['name'] is 'this is a Session example'
?>

After php4.2, you can consider the session to be paid directly:

PHP code:

　　 ＜?PHP
　　 Session_Start();
　　 $_SESSION['name']='value';
　　 ?>

You can cancel the session as follows:

PHP code:

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

There is a BUG in canceling a session variable above php4.2.

Note:

1: no output is allowed before Session_Start () is called. for example, the following is incorrect.
========================================================== =
1 line
2 rows and 3 rows Session_Start (); // The output is already in the first row.
4 rows .....
5 rows?>
========================================================== =

Tip 1:

Any representation '........ headers already sent .......... ', that is, the information output to the browser before Session_Start. the output is normal (the COOKIE will also display this error, and the cause of the error is the same)