In this example we will learn about PHP global variables, what they are and how to use them.\u00a0Variables are an integral part of any programming language. They are used to hold information about the programming context.<\/p>\n
Depending on where the variable is declared, it may be visible or invisible in other parts of the script(the scope of the variable can vary).\u00a0Global Variables or superglobals are visible from any part of the PHP script(they are visible in all scopes)
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\nFor this example we will use:<\/p>\n
Superglobals were introduced in PHP 4.1.0. The superglobals are:<\/p>\n
The index.php<\/em><\/span><\/p>\n In line six and seven we print both local variable and global variable.<\/p>\n The index2.php<\/em><\/span><\/p>\n The comments in the code explains the meaning of each superglobal variable.\u00a0The list below contains some elements that can go inside $_SERVER: This superglobal variable holds the contents of index3.php<\/em><\/span><\/p>\n The $_POST superglobal associative array is used to access all the information sent using the POST method.<\/p>\n index4.php<\/em><\/span><\/p>\n The $_GET superglobal associative array is used to access all the information sent using the GET method.<\/p>\n index5.php<\/em><\/span><\/p>\n Assuming the user entered http:\/\/example.com\/?name=john.\u00a0The above example will output john<\/p>\n This superglobal variable holds items supplied to the script through HTTP POST.<\/p>\n This superglobal variable is an associative array of variables passed to the current script via the environment method.<\/p>\n This is a super global variable which\u00a0is used to manipulate cookie data.<\/p>\n index6.php<\/em><\/span><\/p>\n This checks if index7.php<\/em><\/span><\/p>\n In this example we learnt about PHP global variables. We learnt about $GLOBALS<\/code> superglobal is an associative array which references all global variables in the script. The name of the variable is the key for $GLOBALS<\/code> associative array.<\/p>\n \r\n<?php\r\n$des=\"PHP is a great scripting language.\";\r\n\r\nfunction check(){\r\n$des=\"Java is a great programming language, heard java 9 will be out soon.\";\r\necho \"$des<br>\";\/\/ we print the local variable\r\necho $GLOBALS[\"des\"];\/\/ we print the global variable\r\n\r\n}\r\ncheck();\r\n?>\r\n<\/pre>\n1.2 $_SERVER<\/h3>\n
$_SERVER<\/code> holds server information. Information such as headers, paths and script location.<\/p>\n \r\n <!DOCTYPE html> \r\n<html lang=en>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t \r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t\r\n\t<title>PHP GLOBAL EXAMPLE<\/title>\r\n\t\r\n\t<\/head>\r\n\t<body>\r\n<?php\r\necho $_SERVER [ 'PHP_SELF' ];\/\/ holds the filename about the current executing script\r\necho \"<br>\" ;\r\necho $_SERVER [ 'SERVER_ADDR' ];\/\/holds the ip address of the server which the current script is executing\r\necho \"<br>\" ;\r\necho $_SERVER [ 'SERVER_NAME' ];\/\/ The name of the server host under which the current script is executing.\r\necho \"<br>\" ;\r\necho $_SERVER [ 'REQUEST_METHOD' ];\/\/ Which request method was used to access the page; i.e. ' GET', ' POST \r\necho \"<br>\" ;\r\necho $_SERVER [ 'REQUEST_TIME' ];\r\necho \"<br>\" ;\/\/ The timestamp of the start of the request. Available since PHP 5.1.0.\r\necho $_SERVER [ 'HTTP_HOST' ];\/\/ Contents of the Host: header from the current request, if there is one.\r\necho \"<br>\" ;\r\nif(isset($_SERVER [ 'HTTP_REFERER' ] ))\r\necho $_SERVER [ 'HTTP_REFERER' ];\/\/ The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this\r\necho \"<br>\" ;\r\necho $_SERVER [ 'HTTP_USER_AGENT' ];\/\/ Contents of the User-Agent: header from the current request, if there is one. This is a string denoting the user agent being which is accessing the page.\r\necho \"<br>\" ;\r\necho $_SERVER [ 'SCRIPT_NAME' ];\/\/ Contains the current script's path.\r\n?>\r\n\t<\/body>\r\n\t<\/html>\r\n<\/pre>\n
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\nNote: You may or may not find any of the following elements in $_SERVER .
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\nPHP 5.4.0.<\/li>\n
\nability to modify HTTP_REFERER as a
\nfeature. In short, it cannot really be trusted.<\/li>\n
\ninstance, will change this to whatever your defined secure HTTP port is.<\/li>\n<\/ul>\n1.3 $_REQUEST<\/h3>\n
$_GET<\/code> , $_POST<\/code> and $_COOKIE<\/code><\/p>\n \r\n<!DOCTYPE html> \r\n<html lang=eng>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t \r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t\r\n\t<title>HTML Form<\/title>\r\n\t\r\n\t<\/head>\r\n<body><?php\r\nif ($_SERVER['REQUEST_METHOD' ] == 'POST' ){\r\necho $_REQUEST['name'].\"<br>\";\r\necho $_REQUEST['occu'];\r\n\r\n}\r\nelse{\r\n?>\r\n<form action=<? echo $_SERVER [ 'PHP_SELF' ]; ?> method =\"POST\">\r\n<label for=name>First name<\/label><br>\r\n<input type =\"text\" name =\"name\" id=name required>\r\n<br><br>\r\n<label for=occu>Occupation<\/label><br>\r\n<input type =\"text\" name =\"occu\" required><br><br>\r\n<input type=\"submit\" value=submit>\r\n<\/form>\r\n<?php\r\n}\r\n?>\r\n<\/body>\r\n<\/html>\r\n<\/pre>\n1.4 $_POST<\/h3>\n
\r\n<!DOCTYPE html> \r\n<html lang=eng>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t \r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t\r\n\t<title>HTML Form<\/title>\r\n\t\r\n\t<\/head>\r\n<body><?php\r\nif ($_SERVER['REQUEST_METHOD' ] == 'POST' ){\r\necho $_POST['name'].\"<br>\";\r\necho $_POST['occu'];\r\n\r\n}\r\nelse{\r\n?>\r\n<form action=<? echo $_SERVER [ 'PHP_SELF' ]; ?> method =\"POST\">\r\n<label for=name>First name<\/label><br>\r\n<input type =\"text\" name =\"name\" id=name required>\r\n<br><br>\r\n<label for=occu>Occupation<\/label><br>\r\n<input type =\"text\" name =\"occu\" required><br><br>\r\n<input type=\"submit\" value=submit>\r\n<\/form>\r\n<?php\r\n}\r\n?>\r\n<\/body>\r\n<\/html>\r\n<\/pre>\n1.5 $_GET<\/h3>\n
\r\n\r\n<!DOCTYPE html> \r\n<html lang=eng>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t \r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t\r\n\t<title>HTML Form<\/title>\r\n\t\r\n\t<\/head>\r\n<body>\r\n\r\n<?php\r\necho \t$_GET [ \"name\" ];\r\n?>\r\n<\/body>\r\n<\/html>\r\n<\/pre>\n1.6 $_FILES<\/h3>\n
1.7 $_ENV<\/h3>\n
1.8 $_COOKIE<\/h3>\n
<!DOCTYPE html> \r\n<html lang=eng>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t \r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t\r\n\t<title>superglobal example<\/title>\r\n\t\r\n\t<\/head>\r\n<body>\r\n\r\n<?php\r\nif(isset($_COOKIE[\"name\"]))\r\necho \t$_COOKIE[ \"name\" ];\r\nelse\r\necho \"This cookie is not set\";\r\n?>\r\n<\/body>\r\n<\/html>\r\n<\/pre>\n$_COOKIE[\"name\"]<\/code> is set, if it is set print out it’s value else print out an error message.<\/p>\n1.8 $_SESSION<\/h3>\n
$_SESSION <\/code> is a superglobal which holds session variable.<\/p>\n<?php\r\nsession_start ();\r\n\/* this signifies session has started if you don't write this line, you can't can't use $_Session global variable*\/\r\n$_SESSION [\"name\"]=\"john\";\r\n\/\/prints out the session variable\r\nfunction post(){\r\necho $_SESSION[\"name\"].\"<br>\";\r\n}\r\n\/\/update SESSION variable\r\nfunction change($d){\r\n$_SESSION [ \"name\" ]= $d;\r\n}\r\n?>\r\n<!DOCTYPE html> \r\n<html lang=eng>\r\n\t<head>\r\n\t<style>\r\n\thtml, body{\r\n\twidth:100%;\r\n\theight:100%;\r\n\tmargin:0%;\r\n\tfont-family:\"helvetica\",\"verdana\",\"calibri\", \"san serif\";\r\n\toverflow:hidden;\r\n\tpadding:0%;\r\n\tborder:0%;\r\n\t}\r\n\t<\/style>\r\n\t \t\t<meta charset=\"utf-8\" \/>\r\n\t\t<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, target-densitydpi=device-dpi\"\/>\r\n\t<title>superglobal example<\/title>\r\n\t<\/head>\r\n<body>\r\n<?php\r\npost();\/\/print out session variable\r\nchange(\"mark\");\/\/ update session variable\r\npost();\/\/print out session variable\r\n?>\r\n<\/body>\r\n<\/html>\r\n<\/pre>\n2. Summary<\/h2>\n
$GLOBALS<\/code>, $_SERVER<\/code>, $_REQUEST<\/code>, $_POST<\/code>, $_GET<\/code>, $_FILES<\/code>, $_ENV<\/code>, $_COOKIE\u00a0and<\/span><\/code>\u00a0$_SESSION<\/code><\/p>\n3. Download the source code<\/h2>\n