Just a note, because I didn't know for sure until I tested it.
If you have a query string that contains a parameter but no value (not even an equals sign), like so:
http://path/to/script.php?a
The following script is a good test to determine how a is valued:
<pre>
<?php
print_r($_GET);
if($_GET["a"] === "") echo "a is an empty string\n";
if($_GET["a"] === false) echo "a is false\n";
if($_GET["a"] === null) echo "a is null\n";
if(isset($_GET["a"])) echo "a is set\n";
if(!empty($_GET["a"])) echo "a is not empty";
?>
</pre>
I tested this with script.php?a, and it returned:
a is an empty string
a is set
So note that a parameter with no value associated with, even without an equals sign, is considered to be an empty string (""), isset() returns true for it, and it is considered empty, but not false or null. Seems obvious after the first test, but I just had to make sure.
Of course, if I do not include it in my browser query, the script returns
Array
(
)
a is null
$_GET
$HTTP_GET_VARS [deprecated]
(PHP 4 >= 4.1.0, PHP 5, PHP 7)
$_GET -- $HTTP_GET_VARS [deprecated] — HTTP GET variables
Descrierea
An associative array of variables passed to the current script via the URL parameters (aka. query string). Note that the array is not only populated for GET requests, but rather for all requests with a query string.
$HTTP_GET_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_GET_VARS and $_GET are different variables and that PHP handles them as such)
Exemple
Example #1 $_GET example
<?php
echo 'Hello ' . htmlspecialchars($_GET["name"]) . '!';
?>
Assuming the user entered http://example.com/?name=Hannes
Exemplul de mai sus va afișa ceva similar cu:
Hello Hannes!
Note
Notă:
Aceasta este o variabilă 'superglobală', sau globală automată. Aceasta pur și simplu înseamnă că ea este disponibilă în toate circumstanțele pe parcursul script-ului. Nu este nevoie de a scrie global $variable; pentru a o accesa din funcții sau metode.
Notă:
The GET variables are passed through urldecode().
add a note
User Contributed Notes 5 notes
John Galt ¶
9 years ago
php at securetech dot com dot au ¶
7 days ago
When using $_GET, please consider the security implications of this, as an attacker can post whatever they want, which gets included into your code, unless you are careful and sanitize it and check for VALID values, don't just use whatever is returned.
Instead of using this, i would recommend a function, which will return a sanitized version of the $_GET['variable']
I personally have a function _GET($par, $parType = '')
this means i can swap this into the code for $_GET['variable'] such as _GET('variable')
the function then checks if the second (optional) parameter has been checked:
if($parType == '')
{
$parType = gettype($par);
}
next, we need to sanitize the string, to ensure no really bad stuff can happen. Check the type to ensure we filter correct type of data, for example if type is 'email' then:
$return = filter_input(INPUT_GET, $par, FILTER_SANITIZE_EMAIL)
or
case 'int':
$return = filter_input(INPUT_GET, $par, FILTER_SANITIZE_NUMBER_INT);
you can read some good security information on OWASP, but it isn't targetted to PHP.
timberspine _AT_ gmail _DOT_ com ¶
11 years ago
Note that named anchors are not part of the query string and are never submitted by the browser to the server.
Eg.
http://www.xyz-abc.kz/index.php?title=apocalypse.php#doom
echo $_GET['title'];
// returns "apocalypse.php" and NOT "apocalypse.php#doom"
you would be better off treating the named anchor as another query string variable like so:
http://www.xyz-abc.kz/index.php?title=apocalypse.php&na=doom
...and then retrieve it using something like this:
$url = $_GET['title']."#".$_GET['na'];
Hope this helps someone...
chris at bjelleklang dot org ¶
9 years ago
Please note that PHP setups with the suhosin patch installed will have a default limit of 512 characters for get parameters. Although bad practice, most browsers (including IE) supports URLs up to around 2000 characters, while Apache has a default of 8000.
To add support for long parameters with suhosin, add
suhosin.get.max_value_length = <limit> in php.ini
whatchildisthis ¶
1 year ago
The variable name $_GET is a bit misleading. It works with any HTTP request method that has a query component in the URI: GET, POST, PUT, PATCH, DELETE. A better name would be $_QUERY, similar to http_build_query and PHP_URL_QUERY in parse_url.
