PHP Session Learning Note _php Tutorial

Session refers to the time that a user has spent browsing a website, from entering the website to the browser closing, which is the time it takes for the user to browse the site. From the definition above, we can see that the session is actually a specific time concept.

When the session is used in PHP, the data in the session is stored on the server, and the client's information is identified and extracted through the SessionID from the client.

One instance of yourself

code as follows

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"!--? php session_start ();// To start the session, you must start the $_session[' name ']= "Fangshan" in sessions;//Set the Session,name value to Fangshan ? Next (Save as session.php) !--? php session_start ()//Start session if (isset ($_session[' name '))//determine existence { Echo $_session[' name ']; Echo "del session"; } Else { echo "Session had not been setted"; } ? (save above as session2.php) !--? php session_start ();//Start session Unset ($_session[' name ");//unregister Session variable Session_destroy (); /clear Session ID Header ("Location:session2.php");//Jump back to previous page ? (Save as deletesession.php above)

Common Operations for session:

Session writes, reads, registers, and deletes.

The beginning of the session

The function that marks the beginning of session use is the Session_start,session_start function used to initialize the session variable. The syntax is as follows:

Session_Start ();

The return value is true.

Session Write and read

In PHP, the use of the session is done through the invocation and reading of the predefined array $_session.

In the page of the website, the $_session array is assigned on the registration page, and the $_session array is read on the other pages.

Register the session in the page, for example:

The code is as follows	Copy Code
Session_Start (); $_session[' keyword ']= "PHP"; ?>

A session on another page, for example:

The code is as follows	Copy Code
Session_Start (); echo $_session[' keyword ']; ?>

Run in sequence and the result is:

Php

Session Detection and logoff

Do you remember the isset and unset functions? These two functions implement session detection and logoff respectively.

The ISST function is used to detect if the session is already present and the syntax is as follows:

BOOL Isset ($_session[' session_name ')

For example:

The code is as follows	Copy Code
Session_Start (); if (isset ($_session[' keyword ')) echo $_session[' keyword ']; Else echo "www.bKjia.c0m"; ?>

Results:

Php

The Usset function is used to unregister a session variable that has already been established. The syntax is as follows:

unset ($_session[' session_name '))

For example:

The code is as follows	Copy Code
Session_Start (); unset ($_session[' keyword '); if (isset ($_session[' keyword ')) echo $_session[' keyword ']; Else echo "www.bKjia.c0m"; ?>

Results:

www.bKjia.c0m

There are 10 functions in the PHP processing session, and we'll go through a few more functions.

1, Session_Start

function function: Start a session or return a session that already exists.
Function prototype: Boolean session_start (void);
Return Value: Boolean value
Function Description: This function has no parameters and the return value is true. It is better to put this function first, and before it can have no output, otherwise it will alarm, such as: Warning:cannot send session cache Limiter-headers already sent (output started At/us R/local/apache/htdocs/cga/member/1.php:2) in/usr/local/apache/htdocs/cga/member/1.php on line 3
2, Session_register

function function: Register a new variable as a session variable
Function prototype: Boolean Session_register (string name);
Return value: A Boolean value.
Function Description: This function is to add a variable to the current session in the global variable, the parameter name is the name of the variable you want to add, and success returns the logical value TRUE. You can use $_session[name] or $http_session_vars[name] to take the form of a value or assignment.
3, session_is_registered

function function: Check if the variable is registered as a session variable.
Function prototype: Boobean session_is_registered (string name);
Return Value: Boolean value
Function Description: This function checks to see if a specified variable has been registered in the current session, and the parameter name is the variable name to check. Success returns the logical value TRUE.
4, Session_unregister

function function: Delete the registered variable.
Function prototype: Boolean Session_session_unregister (string name);
Return Value: Boolean value
Function Description: This function removes variables from global variables in the current session. The parameter name is the name of the variable you want to delete, and success returns TRUE.
5, Session_destroy

function function: Ends the current session and empties all resources in the session.
Function Prototype: Boolean session destroy (void);
Return value: A Boolean value.
Function Description: This function ends the current session, this function has no parameters and the return value is True
The functions described above will be used, but there are also some functions about the session:
6, Session_encode

function function: sesssion information encoding
Function prototype: string session_encode (void);
return value: String
Function Description: The returned string contains the names and values of the variables in the global variable, in the form of: A|s:12: "It is a test"; C|s:4: "Lala"; A is the variable name s:12 represents the value of variable a "it is a test length is a semicolon between 12 variables"; Separated.
7, Session_decode

function function: sesssion information decoding
Function prototype: Boolean Session_decode (String data)
Return Value: Boolean value
Function Description: This function can decode session information, and success returns logical value TRUE
8, Session_name

function function: Access the current session name
Function prototype: Boolean session_name (string [name]);
return value: String
Function Description: This function can get or reset the name of the current session. If no parameter name is given, the current session name is obtained, plus the parameter indicates that the session name is set to the parameter name
9, session_id

function function: Access the current session identification number
Function prototype: Boolean session_id (string [id]);
return value: String
Function Description: This function can get or reset the identification number of the session currently stored. If no parameter ID means only the identification number of the current session, plus the parameter indicates that the session's identification number is set to the newly specified ID
10, Session_unset

function function: Delete all registered variables.
Function prototype: void Session_unset (void)
Return Value: Boolean value
Function Description: Unlike Session_destroy, this function does not end the session. It's like using the function Session_unregister to unregister all session variables individually.

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