Recall: Regex Syntax Reference

special chars

|	or
()	grouping
^	start
$	end

quantifiers

*	0 or more
+	1 or more
?	0 or 1
{min,max}	between min and max

character sets

[abcde]	one of those characters
[a-z]	a character from a through z
\d	digit
\s	whitespace

• The next exercise uses regular expressions. (lecture slides)

Exercise : Regular Expressions (by Zack Cava)

Write a regular expression (slides) that would match the following kinds of patterns. You can use the site Rubular to test your regex.

• students' letter grades such as A, B+, or D- (try it) (data)
• DNA (strings of A, C, G, or T) in upper/lower case (try it) (data)
• a US ZIP code (try it) (data)
• a credit card number, with optional dashes every 4 numbers (try it) (data)
• a real number such as 3.14 or -42.8775 (try it) (data)
• dollar amounts of at least $100.00 (try it) (data)
• words that contain at least two vowels (A, E, I, O, or U) (try it) (data)

Exercise Solution

• Grades: /^[abcdf][+-]?$/i
• DNA string: /^[acgt]+$/i
• US ZIP: /^\d{5}(-\d{4})?$/
• Credit Card: /^\d{4}(-?\d{4}){3}$/
• Real Number: /^[-]?\d+(\.\d+)?$/
• $100+: /^\$[1-9]\d{2,}\.\d{2}$/
• Words w/ 2 Vowels: /^[a-z]*[aeiou][a-z]*[aeiou][a-z]*$/i