Lesson 6: Catching some zzz's

Note: Some parts of the repetition syntax below isn't supported in all regular expression implementations.

We've so far learned how to specify the range of characters we want to match, but how about the number of repetitions of characters that we want to match? One way that we can do this is to explicitly spell out exactly how many characters we want, eg. \d\d\d which would match exactly three digits.

A more convenient way is to specify how many repetitions of each character we want using the curly braces notation. For example, a{3} will match the a character exactly three times. Certain regular expression engines will even allow you to specify a range for this repetition such that a{1,3} will match the a character no more than 3 times, but no less than once for example.

This quantifier can be used with any character, or special metacharacters, for example w{3} (three w's), [wxy]{5} (five characters, each of which can be a w, x, or y) and .{2,6} (between two and six of any character).

In the lines below, the last string with only one z isn't what we would consider a proper spelling of the slang "wazzup?". Try writing a pattern that matches only the first two spellings by using the curly brace notation above.

Exercise 6: Matching repeated characters
Task Text  
match wazzzzzup To be completed
match wazzzup To be completed
skip wazup To be completed

There are a couple 'z's in the first two lines we have to match, so the expression waz{3,5}up will match all strings with that many 'z's.

Solve the above task to continue on to the next problem, or read the Solution.