Page 608 - Beginning PHP 5.3

Part III: Using PHP in Practice
If one or more error messages were generated, they are displayed to the user:

if ( $errorMessages ) {
echo “ < p > There was a problem with the form you sent: < /p > < ul > ”;

foreach ( $errorMessages as $errorMessage ) echo “ < li > $errorMessage < /li > ”;
echo ‘ < p > Please < a href=”javascript:history.go(-1)” > go back < /a > and try
again. < /p > ’;

If all was well with the form, a thank - you message is displayed, and the list of ordered products is
shown to the user in expanded form:

} else {
echo “ < p > Thanks for your order! You ordered the following items:
< /p > < ul > ”;

$productCodes = preg_split( “/\W+/”, $_POST[“productCodes”], -1, PREG_
SPLIT_NO_EMPTY );
$products = preg_replace_callback( $productCodePattern,
“expandProductCodes”, $productCodes );
foreach ( $products as $product ) echo “ < li > $product < /li > ”;
echo “ < /ul > ”;
First, preg_split() is used to split the supplied product code string into an array of individual product
codes. The delimiter is a string of one or more non - word characters ( \W+ ). This allows a degree of
flexibility; for example, the user can use a comma to separate the codes, or a comma followed by a space,
or a hyphen.

Next the array of product codes is passed to preg_replace_callback() to turn them into an
array of product names ( $products ). The product code regular expression created earlier
( $productCodePattern ) is used to match the two portions of the product code. The expansion is
handled by the expandProductCodes() function, which is explained in a moment.

Finally, the function loops through the $products array, displaying the product names in an
unordered list.

The expandProductCodes() function defines an array to map the two - letter portion of the product
code to a product range:
$productCodes = array(
“SW” = > “SuperWidget”,
“MW” = > “MegaWidget”,
“WW” = > “WonderWidget”

);
Then it ’ s simply a case of using the array to convert the first subpattern match — $matches[1] — to the

product range string, then returning this string, followed by the string “ model # ”, followed by the
second subpattern match, which is the two - digit product code:

return $productCodes[$matches[1]] . “ model #” . $matches[2];

570

9/21/09 6:18:04 PM
c18.indd 570
c18.indd 570 9/21/09 6:18:04 PM