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Learning PHP 5 by David Sklar

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Chapter 6. Making Web Forms

Form processing is an essential component of almost any web application. Forms are how users communicate with your server: signing up for a new account, searching a forum for all the posts about a particular subject, retrieving a lost password, finding a nearby restaurant or shoemaker, or buying a book.

Using a form in a PHP program is a two-step activity. Step one is to display the form. This involves constructing HTML that has tags for the appropriate user-interface elements in it, such as text boxes, checkboxes, and buttons. If you're not familiar with the HTML required to create forms, the "Forms" chapter in HTML & XHTML: The Definitive Guide, by Chuck Musciano and Bill Kennedy (O'Reilly) is a good place to start.

When a user sees a page with a form in it, she inputs the information into the form and then clicks a button or hits Enter to send the form information back to your server. Processing that submitted form information is step two of the operation.

Example 6-1 is a page that says "Hello" to a user. If a name is submitted, then the page displays a greeting. If a name is not submitted, then the page displays a form with which a user can submit her name.

Example 6-1. Saying "Hello"

if (array_key_exists('my_name',$_POST)) {
    print "Hello, ". $_POST['my_name'];
} else {
    print<<<_HTML_
<form method="post" action="$_SERVER[PHP_SELF]">
 Your name: <input type="text" name="my_name">
<br/>
<input type="submit" value="Say Hello">
</form>
_HTML_;
}

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