PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

4
String Manipulation and Regular
Expressions
IN THIS CHAPTER, WE DISCUSS HOW YOU can use PHP’s string functions to format and
manipulate text.We also discuss using string functions or regular expression functions to
search (and replace) words, phrases, or other patterns within a string.
These functions are useful in many contexts.You often may want to clean up or
reformat user input that is going to be stored in a database. Search functions are great
when building search engine applications (among other things).
Key topics covered in this chapter include
n Formatting strings
n Joining and splitting strings
n Comparing strings
n Matching and replacing substrings with string functions
n Using regular expressions
Creating a Sample Application: Smart Form
Mail
In this chapter, you use string and regular expression functions in the context of a Smart
Form Mail application.You then add these scripts to the Bob’s Auto Parts site you’ve
been building in preceding chapters.
This time, you build a straightforward and commonly used customer feedback form
for Bob’s customers to enter their complaints and compliments, as shown in Figure 4.1.
However, this application has one improvement over many you will find on the Web.
Instead of emailing the form to a generic email address like feedback@example.com,
you’ll attempt to put some intelligence into the process by searching the input for key
words and phrases and then sending the email to the appropriate employee at Bob’s
company. For example, if the email contains the word advertising, you might send the