PHP File Handling, Cookies, and Sessions

PHP I/O File & PHP Cookies and Sessions

• Files store information on a computer, including text, images, and videos
• Files can be categorized based on their type or the content that they hold
• Text files contain plain text (e.g., .txt, .csv)
• Image files contain graphics (e.g., .jpg, .png)
• Executable files hold program instructions (e.g., .exe, .app)

PHP File Functions

• PHP delivers built-in functions for file handling, making tasks like creating, reading, writing, and deleting files simpler
• fopen() opens a file or URL
• fread() reads data from a file
• fwrite() writes data to a file
• fclose() closes an open file

file_exists() Function

• file_exists() checks if a specific file exists on the server
• It returns true if the file is found, and false if not

fopen() Function

• fopen() opens files for reading or writing and needs 2 arguments:
  • The name of the file that you want to open
  • The operating "mode" you want to use on the file

Common File Opening Modes and Functions

• 'r' opens the file for reading only, returns false if the file is non existent, used to read the contents without modifications
• 'r+' opens the file for reading and writing, returns false if the file does not exist, allows modifying
• 'w' opens the file for writing, deleting the content if there is any, creates a new file if not
• 'w+' opens the file for reading and writing, used when you need to read, modify, or add new content, attempts to create if non existent
• 'a' opens the file for writing only, without deleting content, will create files if they do not exist

fread() Function

• fread() reads data from an open file
• Parameters include:
  • File Handle: The file resource, i.e., the name of the file you want to read
  • Length: The maximum amount of bytes you want to read

fgets() Function

• fgets() reads a single line from an open file in PHP
• Returns the resource that is obtained from the fopen() usage
• If the length is not determined when reading the max bytes, the function by default will read the entire line until the finish
• After reading the line, the file gets moved to the current pointer

fwrite() Function

• fwrite() is useful for when you need to write something to a file
• Parameters include:
  • file_name The source file that you want to write the function name to, it has to be opened
  • string Content that you want to write
  • length Used to measure the maximum amount of character

fclose() Function

• fclose() closes files that have been opened
• Closing files will assist in avoiding any system processing issues
• When a file closes the user cannot read or write code using the source, to work on the file again you will need to re-open it using fopen()

PHP I/O File

• "or"- conditional phrase that is used for connecting conditions together
• "die"- a function that stops the current program, and displays a message

PHP File Upload

• $_FILES array is used for handling files in PHP that are uploaded using the POST method
• The array contains information regarding what files are uploaded and the details of each element
• ['name'] tag refers to the name of the file that was uploaded
• ['type'] will return the type of file that was loaded, you can find the data for the files from the HTTP request

PHP File Upload functions and methods

• The filename variable holds the temporary name of the file when its uploaded and the new file will be created copying the file using the method (file_get_contents

PHP File Upload Methods

• Basename to acquire the file name rename(); function, is to rename the temporary file

• The PHP copy function is used to copy files. When writing this make use of file_get_contents to view the names

• The unlink function is used when you want to delete something

PHP Cookies

• A cookie recognizes the user and is small in size but consists of information stored in a client's browser
• It stores electronic visitor information such as browsing data
• Cookies are created on a server side and are also saved to the browsing client
• When a client makes a request, the cookie is embedded in the request

Cookie Uses

• Cookies manage widely used user sessions, such as adding items to an online shopping cart
• They retrieve and set up the expiry date
• Cookies also use http storage in order to customize a search pattern for other users

Cookie Tracking

• Cookies track users in order to analyze high value data such as the location, search history, and the OS that is in use.
• Servers use the data that they store to customize the user experience

How cookies work.

• The browser is the one that stores data on the user's device
• For both sides to be connected, each time you go on the browser you sent an HTTP request which sends the info that is obtained from any stored data

Creating a cookie in PHP

• This function will let users create cookies and direct them to users browsers
• If this functions is used the browsers will need a new cookie file
• If this function is used the browsers will need a new cookie file Super globals will need a cookie

Cookies are used to improve browsing function, and create custom data to improve a certain customer target

Cookies Benefits

• These can be used on the site/marketing by being able to build more targeted ad campaigns, helping companies better target the kind of ads users will buy

PHP Sessions

• Sessions are used to retain user data across different web pages, and can't be passed through a request
• They are more secure than cookies
• Sessions use resources on the web server

Why use Sessions?

• It is an efficient way to manage users and the special secure information associated with them, it helps browsing retain functionality

How do sessions work?

• This is created and managed in the program
• If more sites are open, sessions for different users might be generated

About PHP Sessions

• It is a way to store information, in order to work with PHP files
• After a user leaves a particular page the session gets terminated

Creating Sessions With Code

• Begin by opening the session using session_start()
• Then, check if there is an already established or previously generated session
• The code will verify and check this value, which then generates output if successful

Explore PHP file handling with functions like fopen(), fread(), fwrite(), fclose(), and file_exists(). Understand how to manage files and their contents. Also, learn about cookies and sessions management in PHP.