PHP (Hypertext Pre Processor)
What is PHP:
It is hypertext preprocessor. The scripts are used on the server. PHP file consists of HTML, CSS, JavaScript and PHP code. The extension of PHP is .php.
What can PHP do?
PHP cand generate dynamic page content. It can create, open,read, write, delete and close the files. Php can be used to control user access.
- PHP can be accessed on different platforms like windows, linux etc
PHP variables: Variables can be declared anywhere in the script. The scope of the variable is it can be referenced or used.
There are three types of variables scope where it can be referred to. They are
- local: The variables declared within the function are called local variables. These variables cannot access the outside the function.
- global: The variables declared outside the function are called global variables. These variables only access outside the function.
- static: The static is used when one need a variable to use multiple times and this function makes the variable not to delete the variable from the variable array.
PHP Superglobals:
These are predefined variables which can be accessed from anywhere in the script i.e from any function, class, file.
There are some superglobals:
- $globals: These are variables which are available in all scopes. These can be utilized from every function, class, file. PHP stores all variables in an array called index.
- $
The supergloabals are
- $globals: These superglobal is variable which can be accessed from any function, class, file.
2) $_server: This variable holds the information about header, path, and about the script location.
| Element/Code | Description |
|---|---|
| $_SERVER[‘PHP_SELF’] | Returns the filename of the currently executing script |
| $_SERVER[‘GATEWAY_INTERFACE’] | Returns the version of the Common Gateway Interface (CGI) the server is using |
| $_SERVER[‘SERVER_ADDR’] | Returns the IP address of the host server |
| $_SERVER[‘SERVER_NAME’] | Returns the name of the host server (such as www.w3schools.com) |
| $_SERVER[‘SERVER_SOFTWARE’] | Returns the server identification string (such as Apache/2.2.24) |
| $_SERVER[‘SERVER_PROTOCOL’] | Returns the name and revision of the information protocol (such as HTTP/1.1) |
| $_SERVER[‘REQUEST_METHOD’] | Returns the request method used to access the page (such as POST) |
| $_SERVER[‘REQUEST_TIME’] | Returns the timestamp of the start of the request (such as 1377687496) |
| $_SERVER[‘QUERY_STRING’] | Returns the query string if the page is accessed via a query string |
| $_SERVER[‘HTTP_ACCEPT’] | Returns the Accept header from the current request |
| $_SERVER[‘HTTP_ACCEPT_CHARSET’] | Returns the Accept_Charset header from the current request (such as utf-8,ISO-8859-1) |
| $_SERVER[‘HTTP_HOST’] | Returns the Host header from the current request |
| $_SERVER[‘HTTP_REFERER’] | Returns the complete URL of the current page (not reliable because not all user-agents support it) |
| $_SERVER[‘HTTPS’] | Is the script queried through a secure HTTP protocol |
| $_SERVER[‘REMOTE_ADDR’] | Returns the IP address from where the user is viewing the current page |
| $_SERVER[‘REMOTE_HOST’] | Returns the Host name from where the user is viewing the current page |
| $_SERVER[‘REMOTE_PORT’] | Returns the port being used on the user’s machine to communicate with the web server |
| $_SERVER[‘SCRIPT_FILENAME’] | Returns the absolute pathname of the currently executing script |
| $_SERVER[‘SERVER_ADMIN’] | Returns the value given to the SERVER_ADMIN directive in the web server configuration file (if your script runs on a virtual host, it will be the value defined for that virtual host) (such as someone@w3schools.com) |
| $_SERVER[‘SERVER_PORT’] | Returns the port on the server machine being used by the web server for communication (such as 80) |
| $_SERVER[‘SERVER_SIGNATURE’] | Returns the server version and virtual host name which are added to server-generated pages |
| $_SERVER[‘PATH_TRANSLATED’] | Returns the file system based path to the current script |
| $_SERVER[‘SCRIPT_NAME’] | Returns the path of the current script |
| $_SERVER[‘SCRIPT_URI’] | Returns the URI of the current page |
3) $_post: This variable is used to collect form data after HTML form with method=post. This is used to pass variables.
4) $_request: This variable is used to collect data after submitting the form.
5) $_get: This variable is used to collect the data after submitting form. It can collect the data sent in an URL,