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

128 Chapter 4 String Manipulation and Regular Expressions
Table 4.4 Summary of Special Characters Used in POSIX Regular Expressions
Outside Square Brackets
Character Meaning
\ Escape character
^
Match at start of string
$ Match at end of string
. Match any character except newline (\n)
| Start of alternative branch (read as OR)
( Start subpattern
) End subpattern
* Repeat zero or more times
+ Repeat one or more times
{ Start min/max quantifier
} End min/max quantifier
? Mark a subpattern as optional
Table 4.5 Summary of Special Characters Used in POSIX Regular Expressions Inside
Square Brackets
Character Meaning
\ Escape character
^
NOT, only if used in initial position
- Used to specify character ranges
Putting It All Together for the Smart Form
There are at least two possible uses of regular expressions in the Smart Form application.
The first use is to detect particular terms in the customer feedback.You can be slightly
smarter about this by using regular expressions. Using a string function, you would have
to perform three different searches if you wanted to match on "shop", "customer
service", or "retail".With a regular expression, you can match all three:
shop|customer service|retail
The second use is to validate customer email addresses in the application by encoding
the standardized format of an email address in a regular expression.The format includes
some alphanumeric or punctuation characters, followed by an @ symbol, followed by a
string of alphanumeric and hyphen characters, followed by a dot, followed by more
alphanumeric and hyphen characters and possibly more dots, up until the end of the
string, which encodes as follows:
^[a-zA-Z0-9_\-.]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-.]+$