What is a session in php?
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An alternative way to make data accessible across the various pages of an entire website is to use a PHP Session. Show A session creates a file in a temporary directory on the server where registered session variables and their values are stored. This data will be available to all pages on the site during that visit. The location of the temporary file is determined by a setting in the php.ini file called session.save_path. Before using any session variable make sure you have setup this path. When a session is started following things happen −
When a PHP script wants to retrieve the value from a session variable, PHP automatically gets the unique session identifier string from the PHPSESSID cookie and then looks in its temporary directory for the file bearing that name and a validation can be done by comparing both values. A session ends when the user loses the browser or after leaving the site, the server will terminate the session after a predetermined period of time, commonly 30 minutes duration. Starting a PHP SessionA PHP session is easily started by making a call to the session_start() function.This function first checks if a session is already started and if none is started then it starts one. It is recommended to put the call to session_start() at the beginning of the page. Session variables are stored in associative array called $_SESSION[]. These variables can be accessed during lifetime of a session. The following example starts a session then register a variable called counter that is incremented each time the page is visited during the session. Make use of isset() function to check if session variable is already set or not. Put this code in a test.php file and load this file many times to see the result −
It will produce the following result − You have visited this page 1in this session. Destroying a PHP SessionA PHP session can be destroyed by session_destroy() function. This function does not need any argument and a single call can destroy all the session variables. If you want to destroy a single session variable then you can use unset() function to unset a session variable. Here is the example to unset a single variable − Here is the call which will destroy all the session variables − Turning on Auto SessionYou don't need to call start_session() function to start a session when a user visits your site if you can set session.auto_start variable to 1 in php.ini file. Sessions without cookiesThere may be a case when a user does not allow to store cookies on their machine. So there is another method to send session ID to the browser. Alternatively, you can use the constant SID which is defined if the session started. If the client did not send an appropriate session cookie, it has the form session_name=session_id. Otherwise, it expands to an empty string. Thus, you can embed it unconditionally into URLs. The following example demonstrates how to register a variable, and how to link correctly to another page using SID. It will produce the following result − You have visited this page 1in this session. To continue click following link The htmlspecialchars() may be used when printing the SID in order to prevent XSS related attacks. What is session with example?The definition of a session is a meeting, series of meetings or school term. An example of a session is jury members meeting to agree on a verdict. An example of a session is the time when students are attending classes at school.
What is PHP session and how it works?In PHP, a session provides a way to store web page visitor preferences on a web server in the form of variables that can be used across multiple pages. Unlike a cookie, variable information is not stored on the user's computer.
What is a session explain?In some cases, a session is user-initiated. For example, the time frame for an interaction between two personal computers used in online chatting or messaging is considered a session. The individual users initiate it, and end it when it is finished. Other kinds of sessions are initiated by technology.
What is the use of session start in PHP?PHP - session_start() Function
Sessions or session handling is a way to make the data available across various pages of a web application. The session_start() function is used to start a new session or, resume an existing one.
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