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Unlike with mod_rewrite, when you supply a regular expression to a PHP function you need to enclose

the regular expression definition using a delimiter character. The delimiter character can be any character,

but if the same character needs to appear in the regular expression itself, it must be escaped using the

backslash (

\

) character. The examples here use

#

as the delimiter. So if your expression needs to express

a literal

#

, it should be indicated as

\#

.

Rewriting Numeric URLs with Two Parameters

What you’ve accomplished in the previous exercise is rewriting numeric URLs with one parameter. You

now expand that little example to rewrite URLs with two parameters.

The URLs with one parameter that you supported looked like

http://seophp.example.com/

Products/Pn.html

. Now assume that your links need to support a category ID as well, not only a

product ID. The new URLs will look like this:

http://seophp.example.com/Products/C2/P1.html

The existing

product.php

script will be modified to handle links such as:

http://seophp.example.com/product.php?category_id=2&product_id=1

For a quick reminder, here’s the rewriting rule you used for numeric URLs with one parameter:

RewriteRule ^Products/P([0-9]*)\.html$ /product.php?product_id=$1

PHP Function

Description

preg_match_all

Similar to

preg_match

, but all matches are searched. After one match

is found, the subsequent searches are performed on the rest of the

string. More details at

http://www.php.net/preg_match_all

.

preg_quote

Escapes all special regular expression characters of the input string

using the backslash character. More details at

http://www.php.net/

preg_quote

.

preg_replace

The function replacing matching parts of a string with a replacement

expression. It receives three non-optional parameters: the pattern

used for matching, the replacement expression, and the input string.

More details at

http://www.php.net/preg_replace

.

preg_replace_callback

Similar to

preg_replace

, except instead of a replacement expression,

you specify a function that returns the replacement expression. More

details at

http://www.php.net/preg_replace_callback

.

preg_split

Splits a string on the boundaries matched by a regular expression. The

resulting substrings are returned in the form of an array. More details

at

http://www.php.net/preg_split

.

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Chapter 3: Provocative SE-Friendly URLs

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