PHP Variables and Web Forms

One of the more popular uses of server-side scripts is to process form submissions from web pages. PHP makes it especially easy to bring the values from form fields into your PHP code. Let's take a simple HTML form, a single-line text field where a visitor can enter their e-mail address, as coded in HTML:

<FORM action="process.php3" method="get">
 Please enter your e-mail address: 
 <INPUT type="text" size=20 name="email">
 <BR><INPUT type="submit">
</FORM>

When the above form is submitted, a parameter named "email" with whatever value the user entered will be submitted to the PHP script process.php3. Within that script, a variable named $email will automatically be created with the value from the form:

process.php3:

<?php
 print "Your address, $email, has been added to our mailing list.";
 addToMaillist($email);
?>

Note that addToMaillist is a fictional function, that we might have created to place the user's email address into a text file somewhere.

Because PHP migrates form field names into variables, you may wish to construct form field names with an eye towards their resulting data structure in PHP. For instance, suppose you have one form that asks for information about a recipient of some sort. You may want to contain that form's values inside a $recipient array, for example, to improve data management inside your PHP script:

<FORM action="process.php3" method="get">
 Please enter the recipient's e-mail address: 
 <INPUT type="text" size=20 name="recipient[email]"><BR>
  Please enter the recipient's full name: 
 <INPUT type="text" size=20 name="recipient[name]"><BR>
  <BR><INPUT type="submit">
</FORM>

process.php3:

<?php
 while (list($key,$value) = each($recipient)) {
 	print "$key: $value<BR>";
 }
?>

The HTML form above was migrated into a PHP array named $recipient with the keys email and name. Above, our PHP code simply reproduces the loop we saw earlier and outputs each key and value in this array, for instance (depending on what we submitted in the form):

email: cat@doglover.net
name: Mrs. Kitty

Data collection: Arrays
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