Date, form receiving, session, cookie (php Tutorial 3)

Session

 

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<? Php Session_start (); // The session will expire immediately after the browser is closed. You need to declare it to read and write the session. $ _ Session ['id'] = 'server'; // This is the declaration and initialization, the same as the array usage. $ _ Session ['name'] = 'session '; Print_r ($ _ session); // An array is output after session registration is successful. Echo "<br> "; $ _ Session ['id'] = 'or server'; // change a session and output it. Unset ($ _ session ['name']); // cancel a session and output it. Print_r ($ _ session ); Echo "<br> "; ?>

Session support allows users to register any number of variables and keep them for use by each request. When visitors visit the website, php will automatically (if session. auto_start is set to 1) or when a user request (explicitly called by session_start () or secretly called by session_register () checks whether a specific session id is sent in the request. If yes, the previously saved environment will be rebuilt.

Page1.php

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Session_start (); Echo 'Welcome to page #1 '; /* Create a session variable and assign a value to the session variable */ $ _ Session ['favcolor'] = 'green '; $ _ Session ['Animal '] = 'cat '; $ _ Session ['Time'] = time ();

Page2.php

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Session_start (); Print $ _ session ['Animal ']; // print a single session Var_dump ($ _ session); // Print the session value passed by page1.php.

 

Get,

$ _ Get variable
The $ _ get variable is an array with the variable name and value sent by the http get method.

The $ _ get variable is used to collect the values in the form from method = "get. The information sent from a form with the get method is visible to anyone (displayed in the address bar of the browser), and the amount of information sent is limited (up to 100 characters ).

Example

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<Form action = "welcome. php" method = "get"> Name: <input type = "text" name = "name"/> Age: <input type = "text" name = "age"/> <Input type = "submit"/>

</Form> when a user clicks the submit button, the sent url is similar to the following:

Http://www.111cn.net/welcome.php? Name = peter & age = 37 "welcome. php "files can now get form data through the $ _ get variable (note that the name of the form field will automatically become the id key in the $ _ get array ):

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Welcome <? Php echo $ _ get ["name"];?>. <Br/> You are <? Php echo $ _ get ["age"];?> Years old!

Let's look at a simple and detailed instance.

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<? Php Echo $ str = urlencode ("first page"); // url variable encoding, same as google Echo "<br>". urldecode ($ str); // url variable decoding, I see Echo "<br> <a href = index. php? Page = ". $ str."> page 1 </a> "; Echo "<br> "; If ($ _ get) echo "the variable has been received :". $ _ get ['Page']; // $ _ get corresponds to $ _ post. php automatically recognizes url encoding and decodes it. Echo "<br> "; ?>

Cookie

Php cookie usage
$ Time = time () + 300; // expire in 5 minutes
$ Code = md5 ($ string. $ time. $ salt );
Setcookie ('check _ time', $ time );
Setcookie ('code', $ code );

// Verification
$ Time = time ();
If ($ check_time <$ time) // if the server time is longer than the verification time, it is an expiration date.
// Expire expired
   
If (md5 ($ string. $ check_time. $ salt )! = $ Code)
// Error
In fact, this method is relatively better, because it cannot be submitted after expiration, but it can still be submitted without limit before expiration.

View cookie instances

 

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<? Php Setcookie ("id", "client"); // This is the declaration and cookie initialization function. The browser is disabled. Setcookie ("name", "session", time () + 3600); // expires one hour later Print_r ($ _ cookie); // An array is output after the session registration is successful. You can also access it using $ http_cookie_vars. Echo "<br> "; Setcookie ("id", "or client"); // change a session and output it. Unset ($ _ cookie ['name']); // cancel a session and output it. This is equivalent to setcookie ("name", "", time ()-1 ); this is what many books have said. In fact, unset can also be used to log out. Print_r ($ _ cookie ); Echo "<br> "; ?>

Date

 

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<? Php Echo time (); // returns a string of timestamp in seconds. Echo "<br> "; Echo date ("y-m-d h: I: s", time () + 8*3600); // format time, + 8*3600 to China time zone Echo "<br> "; $ Str = "10:26:10 "; Echo date ("y-m-d h: I: s", strtotime ($ str); // Convert string to timestamp Echo "<br> "; ?>