The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
//Example: <html> <body> <form action="welcome.php" method="post"> Name: <input type="text" name="name" /> Age: <input type="text" name="age" /> <input type="submit" /> </form> </body> </html>
The example HTML page above contains two input fields and a submit button. When the user fills in this form and click on the submit button, the form data is sent to the "welcome.php" file.
The "welcome.php" file looks like this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
// A sample output of the above script may be:
Welcome John.
You are 28 years old.The PHP $_GET and $_POST variables will be explained in the next chapters.
User input should be validated whenever possible. Client side validation is faster, and will reduce server load.
However, any site that gets enough traffic to worry about server resources, may also need to worry about site security. You should always use server side validation if the form accesses a database.
A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form.
This makes it easier to discover the error.
The $_GET variable is used to collect values from a form with method="get".
$_GET Variable :
The $_GET variable is an array of variable names and values sent by the HTTP GET method.
The $_GET variable is used to collect values from 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 it has limits on the amount of information to send (max. 100 characters).
//Example <form action="welcome.php" method="get"> Name: <input type="text" name="name" /> Age: <input type="text" name="age" /> <input type="submit" /> </form>
When the user clicks the "Submit" button, the URL sent could look something like this: http://www.localhost/welcome.php?name=Peter&age=37
The "welcome.php" file can now use the $_GET variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_GET array) :
Welcome <?php echo $_GET["name"]; ?>
You are <?php echo $_GET["age"]; ?> years old!
Why use $_GET :
Note: When using the $_GET variable all variable names and values are displayed in the URL. So this method should not be used when sending passwords or other sensitive information! However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.
Note: The HTTP GET method is not suitable on large variable values; the value cannot exceed 100 characters.
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
Example :
Welcome <?php echo $_REQUEST["name"]; ?>
You are <?php echo $_REQUEST["age"]; ?> years old!
The $_POST variable is used to collect values from a form with method="post".
$_POST Variable :
The $_POST variable is an array of variable names and values sent by the HTTP POST method.
The $_POST variable is used to collect values from a form 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.
//Example <form action="welcome.php" method="post"> Enter your name: <input type="text" name="name" /> Enter your age: <input type="text" name="age" /> <input type="submit" /> </form>
When the user clicks the "Submit" button, the URL will not contain any form data, and will look something like this: http://www.localhost/welcome.php
The "welcome.php" file can now use the $_POST variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_POST array):
Welcome <?php echo $_POST["name"]; ?>
You are <?php echo $_POST["age"]; ?> years old!
Why use $_POST :
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.
$_REQUEST Variable :
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
//Example :
Welcome <?php echo $_REQUEST["name"]; ?>.
You are <?php echo $_REQUEST["age"]; ?> years old!
