Php functions learned today

: This article mainly introduces the php functions learned today. if you are interested in the PHP Tutorial, please refer to them. I have read the TP session implementation and learned the following functions in php!

/*** Mainly used php method * is_array: determines whether it is an array * isset: determines whether the variable is set * --> 1. variable does not exist false * --> 2. the variable exists, but the value is null. false * --> 3. true if the variable exists and the value is not empty * Note:. true * B is returned only when multiple items meet the preceding conditions. after the variable is released by unset, it will no longer be isset * c. this method can only be used for variables and cannot pass any other parameter * difference between this method and empty: empty checks whether a variable is empty * --> 1. returns true if the variable does not exist (different from isset) * --> 2. variable value: ''0'0' null false array () var $ var and object without any attribute true * --> 3. in addition to the preceding two cases, false is returned * Note: only the variable * session_id is used to obtain or set the current session to return the sess. Ion_id () get session_id ('jdjdjjd '); set * session_name: Read or set the session name * session_save_path: Access the current session path * ini_set :( PHP 4, PHP 5, PHP 7) set a value for a configuration option * Note: not all valid options can be changed with ini_set. Here is a list of valid options: http://php.net/manual/zh/ini.list.php * Session_cache_limiter: specifies the buffer control method used by the session page to support the use of * session_cache_expire for back-hop: http://www.php.net/manual/zh/function.session-cache-expire.php * Session_set_save_handler: session_set_save_handler () sets the user-defined session storage function. If you want to use a method other than the built-in session storage mechanism of PHP, * you can use this function. For example, you can customize the session storage function to store session data to the database. * Learning address: http://www.php.net/manual/zh/function.session-set-save-handler.php * Session_regenerate_id: regenerate the session id * session_start: enable session * session_write_close: closing the session can solve the php session blocking problem. article link: http://www.jb51.net/article/48805.htm * Session_unset: releases all the $ _ SESSION variables created in the memory, but does not delete the session file or release the corresponding session * if you only want to release one of the variables, then, use unset ($ _ SESSION ['name']) * session_destroy to delete the session file corresponding to the current user and release the sessionid, the $ _ SESSION variable content in the memory is still reserved * if you want to completely release the session, you need to call session_unset and then call session_destroy * ucwords: convert the first character of each word in the string to uppercase * strpos: locate the first occurrence of a string in another string * strtolower: convert the string to lowercase * is_null: Check whether the variable is NULL * explode: this function cut the string according to the specified string or character separator. Returns the cut string to the array variable * substr: returns a part of the string * Note: garbled characters may occur in the cut Chinese. you can check the mb_substr function to solve this garbled problem ***/

The above describes the php functions learned today, including some content, and hope to help those who are interested in the PHP Tutorial.