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User input should be validated on the browser whenever possible (by
client scripts). Browser validation is faster and reduces the server
load.
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
The $_GET Variable
The predefined $_GET variable is used to collect values in a form with method=”get”
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser’s address bar) and has limits on the amount of information to send.
Example
<form action=”welcome.php” method=”get”>
Name: <input type=”text” name=”fname” />
Age: <input type=”text” name=”age” />
<input type=”submit” />
</form>
When the user clicks the “Submit” button, the URL sent to the server could look something like this:
http://localhost/welcome.php?fname=Peter&age=37
The “welcome.php” file can now use the $_GET variable to collect form data (the names of the form fields will automatically be the keys in the $_GET array):
Welcome <?php echo $_GET["fname"]; ?>.<br />
You are <?php echo $_GET["age"]; ?> years old!
The $_POST Variable
The predefined $_POST variable is used to collect values from a form sent with method=”post”.
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).
Example
<form action=”welcome.php” method=”post”>
Name: <input type=”text” name=”fname” />
Age: <input type=”text” name=”age” />
<input type=”submit” />
</form>
When the user clicks the “Submit” button, the URL will look like this:
http://localhost/welcome.php
The “welcome.php” file can now use the $_POST variable to collect form data (the names of the form fields will automatically be the keys in the $_POST array):
Welcome <?php echo $_POST["fname"]; ?>!<br />
You are <?php echo $_POST["age"]; ?> years old.
The PHP $_REQUEST Variable
The predefined $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST variable can be used to collect form data sent with both the GET and POST methods.
Example
Welcome <?php echo $_REQUEST["fname"]; ?>!<br />
You are <?php echo $_REQUEST["age"]; ?> years old.
PHP $_COOKIE Variable
This variable is often used to identify a user. This is stored on the user’s computer so that every user will be identified if who are they. You can create and get the value of a cookie.
Example
setcookie() function
This function is used to create a cookie. This should appear before the <html> tag.
Syntax:
setcookie (name, value, expire, path, domain);
Example (create a cookie):
<?php
setcookie(“firstname”, “Bryan”, time()+7200);
?> //this should be written before the <html> tag
Here is an example on how to retrieve the value of a cookie:
<?php
echo $_COOKIE[“firstname”];
?>
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
The $_GET Variable
The predefined $_GET variable is used to collect values in a form with method=”get”
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser’s address bar) and has limits on the amount of information to send.
Example
<form action=”welcome.php” method=”get”>
Name: <input type=”text” name=”fname” />
Age: <input type=”text” name=”age” />
<input type=”submit” />
</form>
When the user clicks the “Submit” button, the URL sent to the server could look something like this:
http://localhost/welcome.php?fname=Peter&age=37
The “welcome.php” file can now use the $_GET variable to collect form data (the names of the form fields will automatically be the keys in the $_GET array):
Welcome <?php echo $_GET["fname"]; ?>.<br />
You are <?php echo $_GET["age"]; ?> years old!
The $_POST Variable
The predefined $_POST variable is used to collect values from a form sent with method=”post”.
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).
Example
<form action=”welcome.php” method=”post”>
Name: <input type=”text” name=”fname” />
Age: <input type=”text” name=”age” />
<input type=”submit” />
</form>
When the user clicks the “Submit” button, the URL will look like this:
http://localhost/welcome.php
The “welcome.php” file can now use the $_POST variable to collect form data (the names of the form fields will automatically be the keys in the $_POST array):
Welcome <?php echo $_POST["fname"]; ?>!<br />
You are <?php echo $_POST["age"]; ?> years old.
The PHP $_REQUEST Variable
The predefined $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST variable can be used to collect form data sent with both the GET and POST methods.
Example
Welcome <?php echo $_REQUEST["fname"]; ?>!<br />
You are <?php echo $_REQUEST["age"]; ?> years old.
PHP $_COOKIE Variable
This variable is often used to identify a user. This is stored on the user’s computer so that every user will be identified if who are they. You can create and get the value of a cookie.
Example
setcookie() function
This function is used to create a cookie. This should appear before the <html> tag.
Syntax:
setcookie (name, value, expire, path, domain);
Example (create a cookie):
<?php
setcookie(“firstname”, “Bryan”, time()+7200);
?> //this should be written before the <html> tag
Here is an example on how to retrieve the value of a cookie:
<?php
echo $_COOKIE[“firstname”];
?>
