Regex

Question 1

Ruby Regexp

match any character

Answer 1

.

Question 2

Ruby Regexp

escape regex special characters

Answer 2

\

Question 3

Ruby Regexp

character class delimiter

Answer 3

[]

ex, would look to match any 1 of the set [aeiou] [A-Z] [a-z]

Question 4

Ruby Regexp

create a range within a character class

Answer 4

-

ex [a-z] [A-Z] [0-9]

Question 5

Ruby Regexp

invert the set of characters in a class, i.e. ‘not’

Answer 5

ex [^0-9] [^a-z]

Question 6

Ruby Regexp

anchor that matches the position before the first character of the line

Answer 6

\A or ^

in ruby \A matches the start of the entire string, compared to ^ which will match the start of any line

Question 7

Ruby Regexp

anchor that matches the position after the last character of the string

Answer 7

\z or $

in ruby \z matches the end of the entire string, compared to $ which will match the end of any line

Question 8

Ruby Regexp

anchor that ensures that the following characters match pattern, but doesn’t include those characters in the matched text

Answer 8

(?=pattern)

positive lookahead

Question 9

Ruby Regexp

anchor that ensures that the preceding characters match pattern, but does not include those characters in the matched text

Answer 9

(?<=pattern)

positive lookbehind

Question 10

Ruby Regexp

anchor that ensures that the following characters do not match pattern but doesn’t include them in the matched text

Answer 10

(?!pattern)

negative lookahead

Question 11

Ruby Regexp

anchor that ensures the preceding characters do not match pattern, but doesn’t include those characters in the matched text

Answer 11

(?< !pattern)

negative lookbehind

Question 12

Ruby Regexp

quantifier that makes the previous character optional

Answer 12

?

Question 13

Ruby Regexp

quantifier that specifies one or more of the previous character

Answer 13

+

Question 14

Ruby Regexp

quantifier that specifies zero or more of the previous character

Answer 14

*

Question 15

Ruby Regexp

quantifier that specifies a minimum and maximum number of times the previous character can be repeated

Answer 15

{min,max}

ex

{2,4} # 2 to 4 times

{0,1} # same as ?

{1,} # same as +

{0,} # same as *

{3} # exactly 3 times

Question 16

Ruby Regexp

makes a repetition quantifier lazy instead of greedy

Answer 16

?

Question 17

Ruby Regexp

sequence that escapes a string of characters, matching them as literal characters

Answer 17

\Q…\E

Question 18

Ruby Regexp

alternator symbol in regex

Answer 18

|

Question 19

Ruby Regexp

metacharacter matching a position called ‘word boundary’

Answer 19

\b

Question 20

Ruby Regexp

subtract one characters class from another

Answer 20

[set-[subtract]]

ex [a-z-[aeiou]]

Question 21

Ruby Regexp

with negation and subtraction in a character class, this takes precedence

Answer 21

negation

Question 22

Ruby Regexp

used for grouping / capturing part of a regular expression

Answer 22

(…)

Question 23

Ruby Regexp

used within parentheses so that a group is not captured

Answer 23

?:

ex color=(?:red|green|blue)

Question 24

Ruby Regexp

names a captured group

Answer 24

(?< pattern>)

ex

$(?\d+).(?\d+)

Question 25

# Ruby Regexp uses a named capture later in the regular expression

Answer 25

\k ex /(?[aeiou]).\k.\k/

Question 26

# Ruby Regexp shorthand for [0-9]

Answer 26

\d

Question 27

# Ruby Regexp shorthand for [A-Za-z0-9]

Answer 27

\w

Question 28

# Ruby Regexp shorthand for [\t\r\n\f]

Answer 28

\s # ex space, a tab, a line break, or a form feed, and others depending on flavor of regex

Question 29

# Ruby Regexp shorthand for [^\d]

Answer 29

\D

Question 30

# Ruby Regexp shorthand for [^\w]

Answer 30

\W

Question 31

# Ruby Regexp shorthand for [^\s]

Answer 31

\S

Question 32

# Ruby Regexp regex delimiter in ruby

Answer 32

/expression/

Question 33

# Ruby Regexp regex method that takes a string as an argument and returns the index of the first match in string

Answer 33

Regexp#=~

Question 34

# Ruby Regexp regex / string method that returns a MatchData object

Answer 34

Regexp#match String#match

Question 35

# Ruby Regexp in a MatchData object, returns the original string that was evaluated

Answer 35

MatchData#string #ex m.string

Question 36

# Ruby Regexp in a MatchData object, returns the substring that matched

Answer 36

MatchData#[0] #ex m[0]

Question 37

# Ruby Regexp in a MatchData object, returns the nth capture

Answer 37

MatchData#[n] #ex m[n]

Question 38

# Ruby Regexp string method that takes a regex as an argument and returns an array of substrings delimited by the regex matches (i.e. discards the matches returning an array of each remaining substring)

Answer 38

String#split

Question 39

# Ruby Regexp string method that takes a regex as an argument and returns an array of all of the matches

Answer 39

String#scan

Question 40

# Ruby Regexp how to use named backreferences with Regexp#=~

Answer 40

Ruby creates local variables with the names and values of each named backreferences

Question 41

# Ruby Regexp end delimiter that causes the expression to ignore case

Answer 41

i ex /pattern/i.match('PATTERN')

Question 42

# Ruby Regexp end delimiter that causes the expression to ignore white space and comments in the pattern

Answer 42

x ex /p a t t e r n/x.match('pattern')

Question 43

# Ruby Regexp global variable equivalent to Regexp::last\_match

Answer 43

$~

Question 44

# Ruby Regexp global variable containing the complete matched text, same as Regexp#[0]

Answer 44

$&

Question 45

# Ruby Regexp global variable containing the string before the match, same as Regexp#pre\_match

Answer 45

$`

Question 46

# Ruby Regexp global variable containing the string after the match, same as Regext#post\_match

Answer 46

$'

Question 47

# Ruby Regexp global variables containing nth capture group, same as Regexp#[n]

Answer 47

$n

Question 48

# Ruby Regexp global variable containing last capture group, same as Regexp#[-1]

Answer 48

$+

Question 49

# Ruby Regexp .

Answer 49

match any character

Question 50

# Ruby Regexp \

Answer 50

escape regex special characters

Question 51

# Ruby Regexp [] ex, would look to match any 1 of the set [aeiou] [A-Z] [a-z]

Answer 51

character class delimiter

Question 52

# Ruby Regexp - ex [a-z] [A-Z] [0-9]

Answer 52

create a range within a character class

Question 53

# Ruby Regexp ^ ex [^0-9] [^a-z]

Answer 53

invert the set of characters in a class, i.e. 'not'

Question 54

# Ruby Regexp \A or ^ in ruby \A matches the start of the entire string, compared to ^ which will match the start of any line

Answer 54

anchor that matches the position before the first character of the line

Question 55

# Ruby Regexp \z or $ in ruby \z matches the end of the entire string, compared to $ which will match the end of any line

Answer 55

anchor that matches the position after the last character of the string

Question 56

# Ruby Regexp (?=pattern) positive lookahead

Answer 56

anchor that ensures that the following characters match `pattern`, but doesn't include those characters in the matched text

Question 57

# Ruby Regexp (?\<=pattern) positive lookbehind

Answer 57

anchor that ensures that the preceding characters match `pattern`, but does not include those characters in the matched text

Question 58

# Ruby Regexp negative lookahead (?!pattern)

Answer 58

anchor that ensures that the following characters do not match `pattern` but doesn't include them in the matched text

Question 59

# Ruby Regexp (?\< !pattern) negative lookbehind

Answer 59

anchor that ensures the preceding characters do not match `pattern`, but doesn't include those characters in the matched text

Question 60

# Ruby Regexp ?

Answer 60

quantifier that makes the previous character optional

Question 61

# Ruby Regexp +

Answer 61

quantifier that specifies one or more of the previous character

Question 62

# Ruby Regexp \*

Answer 62

quantifier that specifies zero or more of the previous character

Question 63

# Ruby Regexp {min,max} ex {2,4} # 2 to 4 times {0,1} # same as ? {1,} # same as + {0,} # same as \* {3} # exactly 3 times

Answer 63

quantifier that specifies a minimum and maximum number of times the previous character can be repeated

Question 64

# Ruby Regexp ?

Answer 64

makes a repetition quantifier lazy instead of greedy

Question 65

# Ruby Regexp \Q...\E

Answer 65

sequence that escapes a string of characters, matching them as literal characters

Question 66

# Ruby Regexp |

Answer 66

alternator symbol in regex

Question 67

# Ruby Regexp \b

Answer 67

metacharacter matching a position called 'word boundary'

Question 68

# Ruby Regexp [set-[subtract]] ex [a-z-[aeiou]]

Answer 68

subtract one characters class from another

Question 69

# Ruby Regexp negation

Answer 69

with negation and subtraction in a character class, this takes precedence

Question 70

# Ruby Regexp (...)

Answer 70

used for grouping / capturing part of a regular expression

Question 71

# Ruby Regexp ?: ex color=(?:red|green|blue)

Answer 71

used within parentheses so that a group is not captured

Question 72

# Ruby Regexp (?\< pattern\>) ex \$(?\d+)\.(?\d+)

Answer 72

names a captured group

Question 73

# Ruby Regexp \k ex /(?[aeiou]).\k.\k/

Answer 73

uses a named capture later in the regular expression

Question 74

# Ruby Regexp \d

Answer 74

shorthand for [0-9]

Question 75

# Ruby Regexp \w

Answer 75

shorthand for [A-Za-z0-9]

Question 76

# Ruby Regexp \s # ex space, a tab, a line break, or a form feed, and others depending on flavor of regex

Answer 76

shorthand for [\t\r\n\f]

Question 77

# Ruby Regexp \D

Answer 77

shorthand for [^\d]

Question 78

# Ruby Regexp \W

Answer 78

shorthand for [^\w]

Question 79

# Ruby Regexp \S

Answer 79

shorthand for [^\s]

Question 80

# Ruby Regexp /expression/

Answer 80

regex delimiter in ruby

Question 81

# Ruby Regexp Regexp#=~

Answer 81

regex method that takes a string as an argument and returns the index of the first match in string

Question 82

# Ruby Regexp Regexp#match String#match

Answer 82

regex / string method that returns a MatchData object

Question 83

# Ruby Regexp MatchData#string #ex m.string

Answer 83

in a MatchData object, returns the original string that was evaluated

Question 84

# Ruby Regexp MatchData#[0] #ex m[0]

Answer 84

in a MatchData object, returns the substring that matched

Question 85

# Ruby Regexp MatchData#[n] #ex m[n]

Answer 85

in a MatchData object, returns the nth capture

Question 86

# Ruby Regexp String#split

Answer 86

string method that takes a regex as an argument and returns an array of substrings delimited by the regex matches (i.e. discards the matches returning an array of each remaining substring)

Question 87

# Ruby Regexp String#scan

Answer 87

string method that takes a regex as an argument and returns an array of all of the matches

Question 88

# Ruby Regexp Ruby creates local variables with the names and values of each named backreferences

Answer 88

how to use named backreferences with Regexp#=~

Question 89

# Ruby Regexp i ex /pattern/i.match('PATTERN')

Answer 89

end delimiter that causes the expression to ignore case

Question 90

# Ruby Regexp x ex /p a t t e r n/x.match('pattern')

Answer 90

end delimiter that causes the expression to ignore white space and comments in the pattern

Question 91

# Ruby Regexp $~

Answer 91

global variable equivalent to Regexp::last\_match

Question 92

# Ruby Regexp $&

Answer 92

global variable containing the complete matched text, same as Regexp#[0]

Question 93

# Ruby Regexp $`

Answer 93

global variable containing the string before the match, same as Regexp#pre\_match

Question 94

# Ruby Regexp $'

Answer 94

global variable containing the string after the match, same as Regext#post\_match

Question 95

# Ruby Regexp $n

Answer 95

global variables containing nth capture group, same as Regexp#[n]

Question 96

# Ruby Regexp $+

Answer 96

global variable containing last capture group, same as Regexp#[-1]