Question

Using Python answer the following questions.

1. Describe the class of strings matched by the following regular expressions. Provide examples
that can be captured by the regular expression pattern.
(a) [A-Za-z]+
(b) ^[A-Za-z]+.\d$
2. Which of the following matches regexp /(very )+(thick )?use(ful|less) book/?
Explain why.
A. very thick book
B. very very useful book
C. thick useless book
D. very useless book

Answer 1

1. Describe the class of strings matched by the following regular expressions. Provide examples
that can be captured by the regular expression pattern.
(a) [A-Za-z]+
=> Above Regex match An string which is not empty and contains only alphabets


(b) ^[A-Za-z]+.\d$
=> The regex matches a string which starts with any number of alphabets, then one character of any type, And ending on a digit.


2. Which of the following matches regexp /(very )+(thick )?use(ful|less) book/?
Explain why.
A. very thick book => Does not match, because it does not contain "use"

B. very very useful book => Matches.. Very can be repeated any number of times.. thick is optional. Any of ful or less need to be used.


C. thick useless book
=> Does not mathc, Because very should be occurring 0 or more times.

D. very useless book
=> Matches.. Thick is optional, So it matched.

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