Chapter 6. Forms
Most CGI programs use HTML forms to gather user input.
Forms are comprised of one or more text-input boxes, clickable
radio buttons, multiple-choice checkboxes, and
even pull-down menus and clickable images, all placed inside the
<form>
tag. Within a form, you may also put
regular body content, including text and images. The JavaScript
event handlers can be used in various form elements as well, providing
a number of effects such as testing and verifying form contents.
The <form> Tag
You place a form anywhere inside the body of an
HTML document with its elements enclosed by the
<form>
tag and its respective end tag
</form>
.
All of the form elements within a <form>
tag
comprise a single form. The browser sends all of the values of these
elements--blank, default, or user-modified—when the user
submits the form to the server.
The required action
attribute for
the <form>
tag gives the URL of
the application that is to receive and process the form’s data.
A typical <form>
tag with the
action
attribute looks like this:
<form action="http://www.oreilly.com/cgi-bin/update" > ... </form>
The example URL tells the browser to contact the server named www.oreilly.com and pass along the user’s form values to the application named update, located in the cgi-bin directory.
The browser specially encodes the form’s data before it passes that data to the server so it does not become scrambled or corrupted during the transmission. It is up to the server to either decode the parameters ...
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