PHP Using Strings

1. PHP Using Strings

2. Matching & replacing with string functions Replacing substrings (replace certain parts of a document template; ex <name> with client’s name etc) • mixed str_replace (mixed $needle, mixed $new_needle, mixed $haystack[, int $count] ) • Replaces all instances of $needle in $haystack with $new_needle • Returns a new string = a copy of $haystack with all replacements made • $count has to be a variable (lhs) that will be set to the number of replacements made • $needle, $new_needle, $haystack can be strings or arrays

3. Feeback.html • http://www.nku.edu/~frank/csc301/Examples/PHP_Strings/feedback.html • http://www.nku.edu/~frank/csc301/Examples/PHP_Strings/processfeedback_v2_php.pdf

4. Regular Expressions • The match function is • int preg_match(string $pattern, string $str [, array &$matches [, …]]) • 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 • An optional 3rd argument will capture the actual matched stringand the parenthesized subpatterns, if any. • int preg_match_all(…) • Use to find all matches to the regular expression

5. 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

6. Metacharacters • ^ beginning of string • $ end of string

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

8. 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>"; }

9. Character classes • \d any digit • \D any non-digit • \w Any letter, number, or underscore • \W Anything that is not a letter, number, or underscore • \s whitespace (space, tab, new line, etc.) • \S An y non-whitespace

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>"; }