1. Perl-Compatible Regular Expressions Part 1
Chapter 14
Perl-Compatible Regular Expressions
Part 1

2. preg_match The match function is 1st argument is the pattern
int preg_match(string $pattern, string $str )
1st argument is the pattern
2nd argument is the subject string
Returns number of matches found:
1 (true) if there is a match – it stops at the first match found!
0 (false) otherwise

3. pcre.php
Script 14.1 on page 435
ch14\pcre.php

4. Character Classes [A-Z] uppercase letter [a-z] lowercase letter
[0-9] digit
{5} exactly five
{3,} three or more
{1,4} one to four

5. Metacharacters
^ beginning of string
$ end of string
| or

6. Regular Expression Username – 5 to 10 lowercase letters?
$pattern = '/^[a-z]{5,10}$/';
if (!preg_match($pattern, $username)) {
echo "<p>$username is invalid.</p>"; }

7. Regular Expressions Social Security Number 123-45-6789
$pattern = '/^[0-9]{3}-[0-9]{2}-[0-9]{4}$/';
if (!preg_match($pattern, $ssn)) {
echo "<p>$ssn is invalid.</p>"; }

8. Character classes \d any digit [0-9] \D any non-digit [^0-9]
\w Any letter, number, or underscore [A-Za-z0-9_]
\W Anything that is not a letter, number, or underscore [^A-Za-z0-9_]

9. Character classes
\s whitespace (space, tab, new line, etc.) [\f\r\t\n\v]
\S Any non-whitespace [^\f\r\t\n\v]

10. Regular Expressions Social Security Number 123-45-6789
$pattern = '/^\d{3}-\d{2}-\d{4}$/';
if (!preg_match($pattern, $ssn)) {
echo "<p>$ssn is invalid.</p>"; }

11. Metacharacters [0-9]* * = zero or more [A-Z]+ + = one or more
. . = match any character
([A-Z]\. )? ? = either zero or one

12. Regular Expressions Last name: Frank $pattern = '/^[A-Z][a-z]+$/';
if (!preg_match($pattern, $last)) {
echo "<p>$last is invalid.</p>"; }

13. Regular Expressions Name: Charles Frank or Charles E. Frank
$pattern = '/^[A-Z][a-z]+ ([A-Z]\. )?[A-Z][a-z]+ $/';
if (!preg_match($pattern, $name)) {
echo "<p>$name is invalid.</p>"; }

14. Zip Code
Page 444
/^\d{5}(-\d{4})?$/

15. Address
Page 445