RegExps

Question 1

what two literals are used to create reflexes?

Answer 1

/…/ and %r{…}

Question 2

What is the basic pattern matching operator

Answer 2

=~

Question 3

Which method returns a MatchData object?

Answer 3

match( )

Question 4

How would you write an expression to return a match of “st” in “haystack”?

Answer 4

/st/.match('haystack')
# ==> #

Question 5

What are the 10 metacharacters?

Answer 5

(, ), [, ], {, }, ., ?, +, *

Question 6

What do character classes represent ??

Answer 6

They list characters that may appear at a certain point in the match.

Question 7

Within a character class, what metacharacter denotes an inclusive range of characters?

Answer 7

[a-z][0-9]

Question 8

How do you invert a character match?

Answer 8

Use the ^ (caret) before the character

Question 9

What does inverting the character match do?

Answer 9

It matches any character except the one inverted

Question 10

How can you set an intersection of character classes?

Answer 10

/[a-w]&&[^c-g]z]/

Question 11

Any character except a newline

Answer 11

/./

Question 12

Any character

Answer 12

/./m (m enables multiline mode)

Question 13

A word character

Answer 13

/\w/ ([a-zA-Z0-9_])

Question 14

a NON word character

Answer 14

/\W/ ([^a-zA-Z0-9_])

Question 15

A digit character

Answer 15

/\d/ ( [0-9] )

Question 16

A NON digit character

Answer 16

/\D/ ( [^0-9] )

Question 17

A hexdigit character

Answer 17

([0-9a-fA-F])

Question 18

A NON hexdigit character

Answer 18

([^0-9a-fA-F])

Question 19

A whitespace character

Answer 19

/ [ \t\r\n\f\v ]/

Question 20

A NON whitespace character

Answer 20

/ [^ \t\r\n\f\v ]/