PHP Processing XHTML Forms Introduction A Web form is a common method for allowing the user to provide input As described in XHTML Forms there are two parts to a form the user interface and a script to process the input and ultimately do something meaningful with it This document explains how PHP can be used to process form based input Consult the XHTML Forms document for details about form syntax submission method types i e GET and POST and the types of form widgets Form setup The first step in handling user input via Web forms is to create the user interface The form is typically defined in an XHTML document e g a file that ends with html unless the form itself has dynamic content The action attribute of the form element should be the URL of the PHP script that will be processing the form data Consider the following XHTML markup that defines a form with selection widgets text input widgets and a hidden field Note that the action attribute of the form element designates the PHP script processform php as the recipient of the form data form method post action processform php Radio buttons none pre selected p How would you rate your skill in programming br input type radio name skill value beg Beginner input type radio name skill value int Intermediate input type radio name skill value adv Advanced input type radio name skill value sup Super hacker p Radio buttons one pre selected p How many hours do you spend programming each week br input type radio name hours value 0 10 0 10 br input type radio name hours value 11 20 checked checked 11 20 br input type radio name hours value 21 30 21 30 br input type radio name hours value 30 30 p Checkboxes several p I agree to br input type checkbox input type checkbox input type checkbox input type checkbox br p pre selected name cheaplabor value yes checked checked work for 1 50 hour br name longdays value yes checked checked work 12 hours per day br name late value yes show up late every day br name usecomments value yes checked checked comment my code Menu one selected multiple selections allowed select name state size 5 multiple multiple option value al Alabama option option value ak Alaska option option value as American Samoa option option value az Arizona option option value ar Arkansas option option value ca selected selected California option option value other Some other state option select Text box and password box p Username input type text name username p p Password input type password name passwd p Text area textarea name comments rows 5 cols 40 textarea Hidden field input type hidden name promotion code value x3g9kf43 Submit button p input type submit value Submit the Data p form Now that the user interface has been established the PHP script can be created to process the data Receiving form data Recall that form data is submitted in name value pairs which are derived from the form widgets name and value attributes The standard method for accessing this data is by accessing one of the predefined associative arrays named POST and GET depending on the form submission method used The syntax is POST name where name corresponds to the name attribute of a given form widget Here is a complete PHP script that lists the name value pairs in a table DOCTYPE html PUBLIC W3C DTD XHTML 1 0 Transitional EN http www w3 org TR xhtml1 DTD xhtml1 transitional dtd html xmlns http www w3 org 1999 xhtml head meta http equiv content type content text html charset utf 8 title Programming is Fun title head body h1 Form Results h1 table border 1 tr th Field th th Value th tr php print tr td Skill td td POST skill td tr n print tr td Hours spent programming td td POST hours td tr n print tr td Programming languages used td td POST proglang td tr n print tr td Work for 1 50 hr td td POST cheaplabor td tr n print tr td Work 12 hour days td td POST longdays td tr n print tr td Show up late td td POST late td tr n print tr td Comment your code td td POST usecomments td tr n print tr td State of residence td td POST state td tr n print tr td Username td td POST username td tr n print tr td Password td td POST passwd td tr n print tr td Comments td td POST comments td tr n print tr td Promotion code td td POST promotion code td tr n table body html If a value for a form widget was not specified for example if no text was supplied for the text box named username the value for that entry in the GET or POST associative array will be the empty string The empty string is simply the result of trying to print the value of an undefined key in an associative array Menus with multiple selections When using a menu widget that allows multiple selections an empty pair of brackets must be added to the name attribute of the select element Recall the menu definition from the previous XHTML markup select name state size 5 multiple multiple select If the brackets are omitted only the bottom most selected menu choice will be available via the GET or POST associative arrays For example suppose that three menu options were selected Alabama Alaska and Arkansas Without the brackets the value of POST state is the string Arkansas However if the name attribute s value for the select element is changed to state the value stored in POST state is an array with three string elements There are several things to note here When multiple menu options are selected the form data sent to the server actually contains multiple name value pairs For example the URL encoding for a GET request may look something like the following state alabama state alaska state arkansas The value of POST state will be an array even if only one item in the menu is selected In this case POST state will be an array with one element Arrays will be covered in a later document However there are two concepts worth mentioning at this point 1 If you call print with an array the output will be Array Here is how the output may appear in a browser 2 To display the contents of an array use print r meaning print recursively The output format is rather crude but it allows you to see the contents of the array The modified line of PHP code and example browser output follows print tr td State of residence td td print r POST state print td tr n The requirement of modifying the name attribute seems to be unique to PHP For example Perl s CGI interface automatically converts the multiple selections into an array Useful string functions This section lists common PHP functions that manipulate strings in the context of XHTML forms …
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